diff --git "a/1. Magento Architecture and Customization Techniques/1. Describe Magento\342\200\231s module-based architecture.md" "b/1. Magento Architecture and Customization Techniques/1. Describe Magento\342\200\231s module-based architecture.md"
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-# Magento module overview
->A module is a logical group – that is, a directory containing blocks, controllers, helpers, models – that are related to a specific business feature. In keeping with Magento’s commitment to optimal modularity, a module encapsulates one feature and has minimal dependencies on other modules. - [Magento DevDocs - Module overview](http://devdocs.magento.com/guides/v2.2/architecture/archi_perspectives/components/modules/mod_intro.html)
->
->Modules and themes are the units of customization in Magento. Modules provide business features, with supporting logic, while themes strongly influence user experience and storefront appearance. Both components have a life cycle that allows them to be installed, deleted, and disabled. From the perspective of both merchants and extension developers, modules are the central unit of Magento organization. - [Magento DevDocs - Module overview](http://devdocs.magento.com/guides/v2.2/architecture/archi_perspectives/components/modules/mod_intro.html)
->
->The Magento Framework provides a set of core logic: PHP code, libraries, and the basic functions that are inherited by the modules and other components. - [Magento DevDocs - Module overview](http://devdocs.magento.com/guides/v2.2/architecture/archi_perspectives/components/modules/mod_intro.html)
-
-
-Modules can be installed with Composer allowing their version management. All modules installed in such way are placed in the `vendor/` folder and have next base structure `vendor/<vendor>/<type>-<module-name>`. In this case `<type>` can be:
-1. `module` - Magento module
-1. `theme` - admin or frontend themes
-1. `language` - language packs
-
-In a case when you have a very specific functionality or customisation which is related to a specific project and there is no need to share it with other projects it should be created in the `app/code/<vendor>/<type>-<module-name>` directory and the required directories within it.
-
-### Module registration
-
->Magento components, including modules, themes, and language packages, must be registered in the Magento system through the Magento ComponentRegistrar class. - [Magento DevDocs - Register your component](http://devdocs.magento.com/guides/v2.2/extension-dev-guide/build/component-registration.html)
-
->Each component must have a file called registration.php in its root directory. For example, here is the registration.php file for Magento’s AdminNotification module. Depending on the type of component, registration is performed through registration.php by adding to it as follows: - [Magento DevDocs - Register your component](http://devdocs.magento.com/guides/v2.2/extension-dev-guide/build/component-registration.html)
-
-- How to register modules - registration.php [1]
-```php
-<?php
-
-use \Magento\Framework\Component\ComponentRegistrar;
-
-ComponentRegistrar::register(ComponentRegistrar::MODULE, 'Magento_AdminNotification', __DIR__);
-```
-
-
-- how to register language packages - registration.php [2]
-```php
-<?php
-
-use \Magento\Framework\Component\ComponentRegistrar;
-
- ComponentRegistrar::register(ComponentRegistrar::LANGUAGE, '<VendorName>_<packageName>', __DIR__);
-```
-
-- how to register themes - registration.php [3]
-```php
-<?php
-
-use \Magento\Framework\Component\ComponentRegistrar;
-
- ComponentRegistrar::register(ComponentRegistrar::THEME, '<area>/<vendor>/<theme name>', __DIR__);
-```
-
-
-- composer.json autoload/files[] = "registration.php" [4]
-```json
- {
-"name": "Acme-vendor/bar-component",
-"autoload": {
-    "psr-4": { "AcmeVendor\\BarComponent\\": "" },
-    "files": [ "registration.php" ]
-} }
-```
-
-- at what stage - when including vendor/autoload.php [5]
-```php
-  <?php
-/**
- * Copyright © Magento, Inc. All rights reserved.
- * See COPYING.txt for license details.
- */
-
-\Magento\Framework\Component\ComponentRegistrar::register(
-    \Magento\Framework\Component\ComponentRegistrar::MODULE,
-    'Magento_Backend',
-    __DIR__
-);
-```
-
-- how registered when not in composer - project composer.json autoload/files[] = [app/etc/NonComposerComponentRegistration.php](https://github.com/magento/magento2/blob/2.2/app/etc/NonComposerComponentRegistration.php) [6]
-```json
-    "autoload": {
-        "files": [
-            "app/etc/NonComposerComponentRegistration.php"
-        ],
-    }
-
-```
-
-Examples [1],[2],[3],[4],[5],[6] taken from [Magento DevDocs - Register your component](http://devdocs.magento.com/guides/v2.2/extension-dev-guide/build/component-registration.html)
-
-##### registration.php search paths
-    app/code/*/*/cli_commands.php, registration.php
-    app/design/*/*/*/registration.php
-    app/i18n/*/*/registration.php
-    lib/internal/*/*/registration.php
-    lib/internal/*/*/*/registration.php
-
-##### registration.php load flow
-- pub/index.php
-- app/bootstrap.php
-- app/autoload.php
-- vendor/autoload.php
-- vendor/module[]/registration.php -- last step in Composer init
-- `Magento\Framework\Component\ComponentRegistrar::register(type='module', name='Prince_Productattach', path='/var/www/...')`
-
-# Describe module limitations.
-Minimization of software dependencies is a cornerstone of Magento architecture. Based on this principle there are several logical limitations:
-1. One module is responsible only for one feature.
-1. Module dependencies on other modules must be declared explicitly.
-1. Excluding or disabling a module should not disable another module.
-
-# How do different modules interact with each other?
-Magento 2 is [PSR-4](https://www.php-fig.org/psr/psr-4/) compliant. As a main principle of module interaction Magento 2 declares a dependency injection pattern and service contracts.  
-One of the important parts of module interaction is a Magento area. All components operate with the system and other components in the scope of default areas.
-
-### Module dependencies
-Modules can contain dependencies upon these software components:
-1. Other Magento modules.
-1. PHP extensions.
-1. Third party libraries.
-
-Module dependencies can be managed by:
->1. Name and declare the module in the module.xml file.
->1. Declare any dependencies that the module has (whether on other modules or on a different component) in the module’s composer.json file.
->1. (Optional) Define the desired load order of config files and .css files in the module.xml file.
->
-> -- [Magento DevDocs - Module dependencies](http://devdocs.magento.com/guides/v2.2/architecture/archi_perspectives/components/modules/mod_depend.html) 
-
-> Example: Module A declares a dependency upon Module B. Thus, in Module A’s module.xml file, Module B is listed in the <sequence> list, so that B’s files are loaded before A’s. Additionally, you must declare a dependency upon Module B in A’s composer.json file. Furthermore, in the deployment configuration, Modules A and B must both be defined as enabled. - [Magento DevDocs - Module dependencies](http://devdocs.magento.com/guides/v2.2/architecture/archi_perspectives/components/modules/mod_depend.html)
-
-### Dependency types
-
-##### Hard dependency
-> Modules with a hard dependency on another module cannot function without the module it depends on. 
-Specifically:
->1. The module contains code that directly uses logic from another module (for example, the latter module’s instances, class constants, static methods, public class properties, interfaces, and traits).
->1. The module contains strings that include class names, method names, class constants, class properties, interfaces, and traits from another module.
->1. The module deserializes an object declared in another module.
->1. The module uses or modifies the database tables used by another module.
->
-> -- [Magento DevDocs - Module dependency types](http://devdocs.magento.com/guides/v2.2/architecture/archi_perspectives/components/modules/mod_depend_types.html)
-
-##### Soft dependency
->Modules with a soft dependency on another module can function properly without the other module, even if it has a dependency upon it. Specifically:
->The module directly checks another module’s availability.
->The module extends another module’s configuration.
->The module extends another module’s layout.
->
-> -- [Magento DevDocs - Module dependency types](http://devdocs.magento.com/guides/v2.2/architecture/archi_perspectives/components/modules/mod_depend.html)
-
-Magento module install order flow:
->1. The module serving as a dependency for another module
->2. The module dependent on it
-
-Following dependencies should not be created:
->1. Circular (both direct and indirect)
->1. Undeclared
->1. Incorrect
->
-> -- [Magento DevDocs - Module dependency types](http://devdocs.magento.com/guides/v2.2/architecture/archi_perspectives/components/modules/mod_depend.html) 
-
-
->You can build dependencies between classes in the application layer, but these classes must belong to the same module. Dependencies between the modules of the application layer should be built only by the service contract or the service provider interface (SPI). - [Magento DevDocs - Module dependency types](http://devdocs.magento.com/guides/v2.2/architecture/archi_perspectives/components/modules/mod_depend.html) 
-
-### Magento areas
-A Magento area organizes code for optimized request processing by loading components parts which are related only to the specific area. Areas are registered in the `di.xml` file.
-
->Modules define which resources are visible and accessible in an area, as well as an area’s behavior. The same module can influence several areas. For instance, the RMA module is represented partly in the adminhtml area and partly in the frontend area.
-If your extension works in several different areas, ensure it has separate behavior and view components for each area.
-Each area declares itself within a module. All resources specific for an area are located within the same module as well.
-You can enable or disable an area within a module. If this module is enabled, it injects an area’s routers into the general application’s routing process. 
-If this module is disabled, Magento will not load an area’s routers and, as a result, an area’s resources and specific functionality are not available.
->
-> -- [Magento DevDocs - Modules and areas](http://devdocs.magento.com/guides/v2.2/architecture/archi_perspectives/components/modules/mod_and_areas.html)
-
-Magento has 5 areas types:
-> 1. Magento Admin (`adminhtml`): entry point for this area is index.php or pub/index.php. The Admin panel area includes the code needed for store management. The /app/design/adminhtml directory contains all the code for components you’ll see while working in the Admin panel.
-> 1. Storefront (`frontend`): entry point for this area is index.php or pub/index.php. The storefront (or frontend) contains template and layout files that define the appearance of your storefront.
-> 1. Basic (`base`): used as a fallback for files absent in adminhtml and frontend areas.
-> 1. Cron (`crontab`): In cron.php, the [`\Magento\Framework\App\Cron`](https://github.com/magento/magento2/blob/2.2/lib/internal/Magento/Framework/App/Cron.php#L68-L70) class always loads the 'crontab' area.
->
-> You can also send requests to Magento using the SOAP and REST APIs. These two areas:
-> 1. Web API REST (`webapi_rest`): entry point for this area is index.php or pub/index.php. The REST area has a front controller that understands how to do URL lookups for REST-based URLs.
-> 1. Web API SOAP (`webapi_soap`): entry point for this area is index.php or pub/index.php.
->
-> -- [Magento DevDocs - Modules and areas](http://devdocs.magento.com/guides/v2.2/architecture/archi_perspectives/components/modules/mod_and_areas.html)
-
-Not documented but used in code [Magento/Framework/App/Area.php](
-https://github.com/magento/magento2/blob/2.2/lib/internal/Magento/Framework/App/Area.php#L18-L25):
-1. Documentation (doc). Deprecated.
-1. Admin (admin). Deprecated.
-
-
-# What side effects can come from this interaction?
-- error when module is missing or disabled
-- error when injecting missing class
-- (?) null or error when using object manager for missing class
-  ReflectionException - Class MissingClass does not exist
-  objectManager->create() = new $type() or new $type(...args) --> PHP Warning:  Uncaught Error: Class 'MissingClass' not found
diff --git "a/1. Magento Architecture and Customization Techniques/2. Describe Magento\342\200\231s directory structure.md" "b/1. Magento Architecture and Customization Techniques/2. Describe Magento\342\200\231s directory structure.md"
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-# Determine how to locate different types of files in Magento.
-
->One of the first things you can do to get started with component development is to understand and set up the file system. Each type of component has a different file structure, although all components require certain files.
-In addition, you can choose the component root directory to start development. The following sections have more information. - [Magento DevDocs - About component file structure](https://devdocs.magento.com/guides/v2.2/extension-dev-guide/prepare/prepare_file-str.html)
-
-### Where are the files containing JavaScript, HTML, and PHP located?
-- view/frontend/web/js
-- view/frontend/requirejs-config.js
-- view/frontend/layout
-- view/frontend/templates
-
-### Root directory location
-
->A component’s root directory is the top-level directory for that component under which its folders and files are located. Depending on how your Magento development environment was installed, your component’s root directory can be located in two places: - [Magento DevDocs - Create your component file structure](https://devdocs.magento.com/guides/v2.2/extension-dev-guide/build/module-file-structure.html)
-
-##### `<Magento install directory>/app:` 
-* Modules - app/code.
-* Storefront themes - app/design/frontend.
-* Admin themes - app/design/adminhtml.
-* Language packages - use app/i18n.
-
-##### `<Magento install directory>/vendor`
-
->This location is found in the alternative setups where the composer create-project command was used to get a Magento 2 metapackage (which downloads the CE or EE code), or a compressed Magento 2 archive was extracted in order to install Magento.
->
->Any third party components (and the Magento application itself) are downloaded and stored under the vendor directory. If you are using Git to manage project, this directory is typically added to the .gitignore file. Therefore, we recommend you do your customization work in app/code, not vendor.
->
-> -- [Magento DevDocs - Create your component file structure](https://devdocs.magento.com/guides/v2.2/extension-dev-guide/build/module-file-structure.html)
-
-### Required files
-
->`registration.php`: Among other things, this file specifies the directory in which the component is installed by vendors in production environments. By default, composer automatically installs components in the <Magento root dir>/vendor directory. For more information, see Component registration.
->
->`etc/module.xml`: This file specifies basic information about the component such as the components dependencies and its version number. This version number is used to determine schema and data updates when bin/magento setup:upgrade is run.
->
->`composer.json`: Specifies component dependencies and other metadata. For more information, see Composer integration.
->
-> -- [Magento DevDocs - About component file structure](https://devdocs.magento.com/guides/v2.2/extension-dev-guide/prepare/prepare_file-str.html)
-
-Class [Magento\Framework\Module\ModuleList\Loader](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Module/ModuleList/Loader.php#L78) load `etc/module.xml` files and sort modules by sequence.
-The sequence use for sorting events, plugins, preferences and layouts.
-
-
-### Common directories
-
-- `Api` - Any PHP classes exposed to the API.
-- `Block` - PHP view classes as part of Model View Controller(MVC) vertical implementation of module logic.
-- `Console` - Console commands
-- `Controller` - PHP controller classes as part of MVC vertical implementation of module logic.
-- `Controller/Adminhtml` - Admin controllers
-- `Cron` - Cron job classes
-- `etc` - Configuration files; in particular, module.xml, which is required.
-- `Helper` - Helpers
-- `i18n` - Localization files in CSV format
-- `Model` - PHP model classes as part of MVC vertical implementation of module logic.
-- `Model/ResourceModel` - Database interactions
-- `Observer` - Event listeners
-- `Plugin` - Contains any needed plug-ins.
-- `Setup` - Classes for module database structure and data setup which are invoked when installing or upgrading.
-- `Test` - Unit tests
-- `Ui` - UI component classes
-- `view` - View files, including static view files, design templates, email templates, and layout files.
-  - view/{area}/email
-  - view/{area}/layout
-  - view/{area}/templates
-  - view/{area}/ui_component
-  - view/{area}/ui_component/templates
-  - view/{area}/web
-  - view/{area}/web/template
-  - view/{area}/requirejs-config.js
-
-see [Magento DevDocs - Create your component file structure](https://devdocs.magento.com/guides/v2.2/extension-dev-guide/build/module-file-structure.html)
-
-### Service contract
-
-> The service contract of a module is defined by the set of interfaces in the module’s `/Api` directory.
->
-> This directory contains:
-> 
-> * Service interfaces in the `Api` namespace of the module ([Catalog API](https://github.com/magento/magento2/tree/2.0/app/code/Magento/Customer/Api)).
->
-> * Data (or entity) interfaces in the `Api/Data` directory ([Catalog API/Data](https://github.com/magento/magento2/tree/2.0/app/code/Magento/Customer/Api/Data)). Data entities* are data structures passed to and returned from service interfaces. Files in the data directory contain get() and set() methods for entries in the entity table and extension attributes.
->
-> -- [Service contract anatomy](https://devdocs.magento.com/guides/v2.2/architecture/archi_perspectives/service_layer.html#service-contract-anatomy)
-
-
-
-### Theme file structure
-Example #1
-```
-├── composer.json
-├── theme.xml
-├── etc
-│   └── view.xml
-├── i18n
-│   └── en_US.csv
-├── LICENSE_AFL.txt
-├── LICENSE.txt
-├── media
-│   └── preview.jpg
-├── registration.php
-└── web
-    ├── css
-    │   ├── email.less
-    │   ├── print.less
-    │   ├── source
-    │   │   ├── _actions-toolbar.less
-    │   │   ├── _breadcrumbs.less
-    │   │   ├── _buttons.less
-    │   │   ├── components
-    │   │   │   └── _modals_extend.less
-    │   │   ├── _icons.less
-    │   │   ├── _layout.less
-    │   │   ├── _theme.less
-    │   │   ├── _tooltips.less
-    │   │   ├── _typography.less
-    │   │   └── _variables.less
-    │   ├── _styles.less
-    │   ├── styles-l.less
-    │   └── styles-m.less
-    ├── images
-    │   └── logo.svg
-    └── js
-        ├── navigation-menu.js
-        ├── responsive.js
-        └── theme.js
-```
-
-### Language package file structure
-Example #2
-```
-├── de_DE
-│   ├── composer.json
-│   ├── language.xml
-│   ├── LICENSE_AFL.txt
-│   ├── LICENSE.txt
-│   └── registration.php
-├── en_US
-│   ├── composer.json
-│   ├── language.xml
-│   ├── LICENSE_AFL.txt
-│   ├── LICENSE.txt
-│   └── registration.php
-├── pt_BR
-│   ├── composer.json
-│   ├── language.xml
-│   ├── LICENSE_AFL.txt
-│   ├── LICENSE.txt
-│   └── registration.php
-```
-
-Examples #1, #2 - - [Magento DevDocs - Create your component file structure](https://devdocs.magento.com/guides/v2.2/extension-dev-guide/build/module-file-structure.html)
diff --git a/1. Magento Architecture and Customization Techniques/3. Utilize configuration XML and variables scope.md b/1. Magento Architecture and Customization Techniques/3. Utilize configuration XML and variables scope.md
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-# Determine how to use configuration files in Magento. Which configuration files correspond to different features and functionality?
-
-### List of existed *.xml configs
-- `acl.xml` - resource title, sort
-- `adminhtml/rules/payment_{country}.xml` - paypal
-- `address_formats.xml`
-- `address_types.xml` - format code and title only
-- `cache.xml` - name, instance - e.g. full_page=Page Cache
-- `catalog_attributes.xml` - catalog_category, catalog_product, unassignable, used_in_autogeneration, quote_item [*](https://www.atwix.com/magento-2/how-to-access-custom-catalog-attributes/)
-- `communication.xml`
-- `config.xml` - defaults
-- `crontab.xml` - group[], job instance, method, schedule [*](https://github.com/magento-notes/magento2-exam-notes/blob/master/1.%20Magento%20Architecture%20and%20Customization%20Techniques/6.%20Configure%20event%20observers%20and%20scheduled%20jobs.md#crontabxml)
-- `cron_groups.xml` [*](https://github.com/magento-notes/magento2-exam-notes/blob/master/1.%20Magento%20Architecture%20and%20Customization%20Techniques/6.%20Configure%20event%20observers%20and%20scheduled%20jobs.md#cron-groups)
-- `di.xml` - preference, plugins, virtual type [*](https://devdocs.magento.com/guides/v2.2/extension-dev-guide/build/di-xml-file.html)
-- `eav_attributes.xml` - locked entity attributes (global, unique etc.)
-- `email_templates.xml` - id label file type module -- view/frontend/email/name.html
-- `events.xml` - observers, shared, disabled [*](https://github.com/magento-notes/magento2-exam-notes/blob/master/1.%20Magento%20Architecture%20and%20Customization%20Techniques/6.%20Configure%20event%20observers%20and%20scheduled%20jobs.md#demonstrate-how-to-configure-observers)
-- `export.xml`
-- `extension_attributes.xml` - for, attribute code, attribute type
-- `fieldset.xml`
-- `import.xml`
-- `indexer.xml` - class, view_id, title, description
-- `integration.xml`
-- `integration/api.xml`
-- `integration/config.xml`
-- `menu.xml` - admin menu
-- `module.xml` - version, sequence
-- `mview.xml` - scheduled updates, subscribe to table changes, indexer model
-- `page_types.xml`
-- `payment.xml` - groups, method allow_multiple_address
-- `pdf.xml` - renders by type (invoice, shipment, creditmemo) and product type
-- `product_types.xml` - label, model instance, index priority, (?) custom attributes, (!) composable types
-- `product_options.xml`
-- `resources.xml`
-- `routes.xml`
-- `sales.xml` - collectors (quote, order, invoice, credit memo)
-- `search_engine.xml`
-- `search_request.xml` - index, dimensions, queries, filters, aggregations, buckets
-- `sections.xml` - action route placeholder -> invalidate customer sections
-- `system.xml` - adminhtml config
-- `validation.xml` - entity, rules, constraints -> class
-- `view.xml` - vars by module
-- `webapi.xml` - route, method, service class and method, resources
-- `widget.xml` - class, email compatible, image, ttl (?), label, description, parameters
-- `zip_codes.xml`
-
-# Interfaces for work with configs
-
-#### [\Magento\Framework\Config\Reader\Filesystem](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Config/Reader/Filesystem.php) -> [\Magento\Framework\Config\ReaderInterface](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Config/ReaderInterface.php)
-Gets .xsd names from schema locator, gets full .xml file list from file resolver, merges all files, validates, runs converter to get resulting array.
-- read(scope)
-  + `fileResolver->get(_filename)`
-  + merge and validate each file (if mode developer)
-  + validate merged DOM
-  + converter->convert(dom) => array
-- `_idAttributes`, `_fileName`, `_schemaFile` (from schemaLocator), `_perFileSchema` (from schemaLocator), filename (menu.xml)
-- schemaFile from schemaLocator
-
-#### [\Magento\Framework\Config\ConverterInterface](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Config/ConverterInterface.php)
-Convert an array to any format
-- `convert(\DOMDocument $source)`
-
-#### [\Magento\Framework\Config\SchemaLocatorInterface](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Config/SchemaLocatorInterface.php) - full path to .xsd
-- `getPerFileSchema` - per file before merge
-- `getSchema` - merged file
-
-#### [\Magento\Framework\Config\ValidationStateInterface](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Config/ValidationStateInterface.php)
-
-This interface retrieves the validation state.
-- `isValidationRequired()`
-
-[\Magento\Framework\App\Arguments\ValidationState](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/App/Arguments/ValidationState.php) is default implementation, that require validation only in developer mode.
-
-#### [\Magento\Framework\Config\ScopeListInterface](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Config/ScopeListInterface.php)
-
-This interface the list of all scopes.
-- `getAllScopes()`
-
-#### [\Magento\Framework\Config\Data](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Config/Data.php) -> [\Magento\Framework\Config\DataInterface](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Config/DataInterface.php)
-
-Helps to get the configuration data in a specified scope.
-- `merge(array $config);`
-- `get($key, $default = null)`
-
-
-###### Links and examples:
-- Product types configs model to read data from [product_types.xml](https://github.com/magento/magento2/blob/2.3/app/code/Magento/Catalog/etc/product_types.xml): [\Magento\Catalog\Model\ProductTypes](https://github.com/magento/magento2/tree/2.3/app/code/Magento/Catalog/Model/ProductTypes) 
-- Implementation via virtual types to read data from layout.xml: [Magento/Theme/etc/di.xml](https://github.com/magento/magento2/blob/2.3/app/code/Magento/Theme/etc/di.xml#L42)
-- https://www.atwix.com/magento-2/working-with-custom-configuration-files/
-
-
-### Configuration load and merge flow
-
-#### Loading order
- 1. First step is a `app/etc/di.xml` loading
- 1. Next step is collecting configuration files from all modules and merging them: `vendor_name/component_name/etc/*.xml`
- 1. At the last step Magento will collect all configs from `vendor_name/component_name/etc/<area>/*.xml`
-
-#### Merge flow
-
->Nodes in configuration files are merged based on their fully qualified XPaths, which has a special attribute defined in $idAttributes array declared as its identifier. This identifier must be unique for all nodes nested under the same parent node.
->
-> * If node identifiers are equal (or if there is no identifier defined), all underlying content in the node (attributes, child nodes, and scalar content) is overridden.
-> * If node identifiers are not equal, the node is a new child of the parent node.
-> * If the original document has multiple nodes with the same identifier, an error is triggered because the identifiers cannot be distinguished.
-> * After configuration files are merged, the resulting document contains all nodes from the original files.
->
-> -- [Magento DevDocs - Module configuration files](https://devdocs.magento.com/guides/v2.2/config-guide/config/config-files.html)
-
-config merger = \Magento\Framework\Config\Dom
-- when merging each file
-  + createConfigMerger|merge
-  + \Magento\Framework\Config\Dom::_initDom(dom, perFileSchema)
-  + \Magento\Framework\Config\Dom::validateDomDocument
-  + $dom->schemaValidate
-- after all merged
-  + \Magento\Framework\Config\Dom::validate(mergedSchema)
-  + \Magento\Framework\Config\Dom::validateDomDocument
-  
-## Sensitive and environment settings
-
-This scope is a very huge part which includes a lot of things and there is a short list of useful links
-to the official Magento DevDocs documentation:
-
-- [Set configuration values](https://devdocs.magento.com/guides/v2.2/config-guide/cli/config-cli-subcommands-config-mgmt-set.html)
-- [Sensitive and system-specific](https://devdocs.magento.com/guides/v2.2/config-guide/prod/config-reference-sens.html)
-- [Magento Enterprise B2B Extension configuration paths reference](https://devdocs.magento.com/guides/v2.2/config-guide/prod/config-reference-b2b.html)
-- [Other configuration paths reference](https://devdocs.magento.com/guides/v2.2/config-guide/prod/config-reference-most.html)
-
-### Example of how to set sensitive settings
-
-- shared config app/etc/config.php
-- sensitive or system-specific app/etc/env.php:
-
-```xml
-    <type name="Magento\Config\Model\Config\TypePool">
-       <arguments>
-          <!-- sensitive config items -->
-          <argument name="sensitive" xsi:type="array">
-             <item name="payment/paypal_express/merchant_id" xsi:type="string">1</item>
-             <!-- keys, password, emails, personally identifiable information -->
-          </argument>
-          <!-- environment specific config items -->
-          <argument name="environment" xsi:type="array">
-             <item name="payment/paypal_express/debug" xsi:type="string">1</item>
-             <!-- URLs, IPs, hosts, modes sandbox/live, email recipients -->
-          </argument>
-       </arguments>
-    </type>
-```
-
- Sensitive info doesn't get exported with `bin/magento app:config:dump`. use env. params, e.g.
-`CONFIG__DEFAULT__PAYMENT__TEST__PASWORD` for `payment/test/password`
-
-`bin/magento app:config:dump`:
-
-- system-specific > app/etc/env.php
-- shared > app/etc/config.php
-- sensitive - skipped
-
-`bin/magento config:sensitive:set`:
-
-- writes to app/etc/env.php
diff --git a/1. Magento Architecture and Customization Techniques/4. Demonstrate how to use dependency injection.md b/1. Magento Architecture and Customization Techniques/4. Demonstrate how to use dependency injection.md
deleted file mode 100644
index d3c7c92..0000000
--- a/1. Magento Architecture and Customization Techniques/4. Demonstrate how to use dependency injection.md	
+++ /dev/null
@@ -1,58 +0,0 @@
-# Demonstrate how to use dependency injection
-
-Magento 2 uses constructor injection, where all injected objects or factories are provided when the object is constructed.
-
-Magento loads di.xml files and merges them all together from the following stages:
-* Initial (app/etc/di.xml)
-* Global ({moduleDir}/etc/di.xml)
-* Area-specific ({moduleDir}/etc/{area}/di.xml)
-
-### Object manager
-
-Under the hood, the [ObjectManager](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/ObjectManager/ObjectManager.php) 
-will use PHP reflection features to look at a class’s __construct type hints/parameters, 
-automatically instantiate the object for us, and then pass it into the constructor as an argument.
-
-[AbstractFactory](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/ObjectManager/Factory/AbstractFactory.php) > [\Magento\Framework\ObjectManager\FactoryInterface](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/ObjectManager/FactoryInterface.php)
-and their implementations use to resolve arguments and create new objects.
-
-By default, all objects created via automatic constructor dependency injection are singleton objects,
-because they created via ObjectManager::get() method.
-
-```
-if ($isShared) {
-    $argument = $this->objectManager->get($argumentType);
-} else {
-    $argument = $this->objectManager->create($argumentType);
-}
-```
-[\Magento\Framework\ObjectManager\Factory::resolveArgument()](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/ObjectManager/Factory/AbstractFactory.php#L143-L147)
-
-### Arguments
-
-```
-    <argument xsi:type="object">{typeName}</argument>
-    <argument xsi:type="object" shared="{shared}">{typeName}</argument>
-
-    <argument xsi:type="string">{strValue}</argument>
-    <argument xsi:type="string" translate="true">{strValue}</argument>
-
-    <argument xsi:type="boolean">{boolValue}</argument>
-    <argument xsi:type="number">{numericValue}</argument>
-    <argument xsi:type="init_parameter">{Constant::NAME}</argument>
-    <argument xsi:type="const">{Constant::NAME}</argument>
-    <argument xsi:type="null"/>
-
-    <argument xsi:type="array">
-      <item name="someKey" xsi:type="<type>">someVal</item>
-    </argument>
-```
-
-###### Links
-- [Dependency injection](https://devdocs.magento.com/guides/v2.2/extension-dev-guide/depend-inj.html)
-- [The di.xml file](https://devdocs.magento.com/guides/v2.2/extension-dev-guide/build/di-xml-file.html)
-- [ObjectManager](https://devdocs.magento.com/guides/v2.2/extension-dev-guide/object-manager.html)
-- [Proxies](https://devdocs.magento.com/guides/v2.2/extension-dev-guide/proxies.html)
-- [Factories](https://devdocs.magento.com/guides/v2.2/extension-dev-guide/factories.html)
-- [Alan Storm, The Magento 2 Object System](https://alanstorm.com/category/magento-2/#magento-2-object-system)
-- [Alan Kent, Magento 2 Dependency injection](https://alankent.me/2014/06/07/magento-2-dependency-injection-the-m2-way-to-replace-api-implementations/)
diff --git a/1. Magento Architecture and Customization Techniques/5. Demonstrate ability to use plugins.md b/1. Magento Architecture and Customization Techniques/5. Demonstrate ability to use plugins.md
deleted file mode 100644
index 33ee2a7..0000000
--- a/1. Magento Architecture and Customization Techniques/5. Demonstrate ability to use plugins.md	
+++ /dev/null
@@ -1,210 +0,0 @@
-# Demonstrate ability to use plugins
-
-There are three types of plugins in magento: around, before and after.
-
-__Important__: Classes, abstract classes and interfaces that are implementations of or inherit from classes that have plugins will also inherit plugins from the parent class.
-For example, if you create a plugin for [\Magento\Catalog\Block\Product\AbstractProduct](https://github.com/magento/magento2/blob/2.3/app/code/Magento/Catalog/Block/Product/AbstractProduct.php),
-plugin methods will be called for all child classes, such as \Magento\Catalog\Block\Product\View, \Magento\Catalog\Block\Product\ProductList\Upsell etc.
-
-### Limitations
-
-Plugins only work on __public methods__ for any __classes__ or __interfaces__. 
-So plugins can not be used on following:
-
-> 1. Final methods
-> 1. Final classes
-> 1. Non-public methods
-> 1. Class methods (such as static methods)
-> 1. __construct
-> 1. Virtual types
-> 1. Objects that are instantiated before Magento\Framework\Interception is bootstrapped
-
-@since 2.2 *after* plugin has access to *arguments*! 
-
-### Prioritizing plugins
-
-The `sortOrder` property controls how your plugin interacts with other plugins on the same class. 
-
-> The prioritization rules for ordering plugins:
->
-> * Before the execution of the observed method, Magento will execute plugins from lowest to greatest `sortOrder`.
->
->   * During each plugin execution, Magento executes the current plugin's before method.
->   * After the before plugin completes execution, the current plugin's around method will wrap and execute the next plugin or observed method.
->
-> * Following the execution of the observed method, Magento will execute plugins from greatest to lowest `sortOrder`.
->
->   * During each plugin execution, the current plugin will first finish executing its around method.
->   * When the around method completes, the plugin executes its after method before moving on to the next plugin.
->
-> -- [Magento DevDocs - Plugins](https://devdocs.magento.com/guides/v2.2/extension-dev-guide/plugins.html#prioritizing-plugins)
-
-Plugin sortOrder:
-
-- before sortOrder=10, before sortOrder=20, before sortOrder=30 ...
-- before and around (first half) called together for same plugin!
-- around (second half) and after called together for same plugin!
-
-Example:
-
-- pluginA.beforeMethod, pluginA.aroundMethod first half
-- pluginB.beforeMethod, pluginB.aroundMethod first half
-- pluginC.beforeMethod, `____________________
-- ____________________, pluginD.aroundMethod first half
-- method()
-- ____________________, pluginD.aroundMethod second half
-- pluginC.afterMethod , ________________________________
-- pluginB.aroundMethod second half, pluginB.afterMethod
-- pluginA.aroundMethod second half, pluginA.afterMethod
-
-### Identify strengths and weaknesses of plugins.
-
-> The greatest weakness is exploited in the hands of a developer who is either not
-> experienced or not willing to take the time to evaluate the fallout. For example,
-> used improperly, an around plugin can prevent the system from functioning.
-> They can also make understanding what is going on by reading source code hard
-> (spooky action at a distance).
->
-> -- [Swiftotter Developer Study Guide](https://swiftotter.com/technical/certifications/magento-2-certified-developer-study-guide)
-
-Using around plugins:
-> Avoid using around method plugins when they are not required because they increase stack traces and affect performance. 
-> The only use case for around method plugins is when you need to terminate the execution of all further plugins and original methods.
->
-> -- [Magento DevDocs - Programming Best Practices](https://devdocs.magento.com/guides/v2.2/ext-best-practices/extension-coding/common-programming-bp.html#using-around-plugins)
-
-### In which cases should plugins be avoided?
-
-> Plugins are useful to modify the input, output, or execution of an existing method.
-> Plugins are also best to be avoided in situations where an event observer will work.
-> Events work well when the flow of data does not have to be modified.
->
-> -- [Swiftotter Developer Study Guide](https://swiftotter.com/technical/certifications/magento-2-certified-developer-study-guide)
-
-Info from Magento technical guidelines:
-> `4. Interception`
-> 
-> 4.1. Around-plugins SHOULD only be used when behavior of an original method is supposed to be substituted in certain scenarios.
-> 
-> 4.2. Plugins SHOULD NOT be used within own module .
-> 
-> 4.3. Plugins SHOULD NOT be added to data objects.
-> 
-> 4.4. Plugins MUST be stateless.
->
-> ...
-> 
-> `14. Events`
-> 
-> 14.1. All values (including objects) passed to an event MUST NOT be modified in the event observer. Instead, plugins SHOULD BE used for modifying the input or output of a function.
->
-> -- [Magento DevDocs - Technical guidelines](https://devdocs.magento.com/guides/v2.2/coding-standards/technical-guidelines.html)
-
-
-Also check:
-- [Yireo - Magent 2 observer or Plugin?](https://www.yireo.com/blog/1875-magent-2-observer-or-plugin)
-- [Magento DevDocs - Observers Best Practices](https://devdocs.magento.com/guides/v2.2/ext-best-practices/extension-coding/observers-bp.html)
-
-
-### how it works?
-
-Magento automatically generates `Interceptor` class for the plugin target and store it in the `generated\code` directory.
-
-```
-    namespace \Notes;
-
-    class Interceptor extends \Notes\MyBeautifulClass implements \Magento\Framework\Interception\InterceptorInterface
-    {
-        use \Magento\Framework\Interception\Interceptor;
-
-        public function __construct($specificArguments1, $someArg2 = null)
-        {
-            $this->___init();
-            parent:__construct($specificArguments1, $someArg2);
-        }
-
-        public function sayHello()
-        {
-            pluginInfo = pluginList->getNext('MyBeautifulClass', 'sayHello')
-            __callPlugins('sayHello', [args], pluginInfo)
-        }
-    }
-```
-
-[\Magento\Framework\Interception\Interceptor](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Interception/Interceptor.php):
-
-- $pluginList = [\Magento\Framework\Interception\PluginListInterface](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Interception/PluginListInterface.php)
-- $subjectType = 'MyBeautifulClass'
-- `___init` - called in in constructor, pluginList = get from object manager, subjectType = class name
-- pluginList->getNext
-- `___callPlugins`
-- `___callParent`
-
-### how generated?
-
-    \Magento\Framework\App\Bootstrap::create
-    \Magento\Framework\App\Bootstrap::__construct
-    \Magento\Framework\App\ObjectManagerFactory::create
-    \Magento\Framework\ObjectManager\DefinitionFactory::createClassDefinition
-        \Magento\Framework\ObjectManager\DefinitionFactory::getCodeGenerator
-        \Magento\Framework\Code\Generator\Io::__construct
-        \Magento\Framework\Code\Generator::__construct
-        spl_autoload_register([new \Magento\Framework\Code\Generator\Autoloader, 'load']);
-
-    \Magento\Framework\App\ObjectManagerFactory::create
-    \Magento\Framework\Code\Generator::setGeneratedEntities
-    \Magento\Framework\App\ObjectManager\Environment\Developer::configureObjectManager
-
-    \Magento\Framework\Code\Generator\Autoloader::load
-    \Magento\Framework\Code\Generator::generateClass
-
-### Decide how to generate based on file suffix - generator \Magento\Framework\Code\Generator\EntityAbstract
-```
-array (
-  'extensionInterfaceFactory' => '\\Magento\\Framework\\Api\\Code\\Generator\\ExtensionAttributesInterfaceFactoryGenerator',
-  'factory' => '\\Magento\\Framework\\ObjectManager\\Code\\Generator\\Factory',
-  'proxy' => '\\Magento\\Framework\\ObjectManager\\Code\\Generator\\Proxy',
-  'interceptor' => '\\Magento\\Framework\\Interception\\Code\\Generator\\Interceptor',
-  'logger' => '\\Magento\\Framework\\ObjectManager\\Profiler\\Code\\Generator\\Logger',
-    - logs all public methods call
-    - Magento\Framework\ObjectManager\Factory\Log -- missing?
-  'mapper' => '\\Magento\\Framework\\Api\\Code\\Generator\\Mapper',
-    - extractDto() = $this->{$name}Builder->populateWithArray()->create
-  'persistor' => '\\Magento\\Framework\\ObjectManager\\Code\\Generator\\Persistor',
-    - getConnection, loadEntity, registerDelete, registerNew, registerFromArray, doPersist, doPersistEntity
-  'repository' => '\\Magento\\Framework\\ObjectManager\\Code\\Generator\\Repository', -- deprecated
-  'convertor' => '\\Magento\\Framework\\ObjectManager\\Code\\Generator\\Converter',
-    - Extract data object from model
-    - getModel(AbstractExtensibleObject $dataObject) = getProductFactory()->create()->setData($dataObject)->__toArray()
-  'searchResults' => '\\Magento\\Framework\\Api\\Code\\Generator\\SearchResults',
-    - extends \Magento\Framework\Api\SearchResults
-  'extensionInterface' => '\\Magento\\Framework\\Api\\Code\\Generator\\ExtensionAttributesInterfaceGenerator',
-  'extension' => '\\Magento\\Framework\\Api\\Code\\Generator\\ExtensionAttributesGenerator',
-    - extension_attributes.xml
-    - extends \Magento\Framework\Api\AbstractSimpleObject
-    - implements {name}\ExtensionInterface
-    - for every custom attribute, getters and setters
-  'remote' => '\\Magento\\Framework\\MessageQueue\\Code\\Generator\\RemoteServiceGenerator',
-)
-```
-
-```
-Magento\Framework\App\ResourceConnection\Proxy -> type Proxy, name Magento\Framework\App\ResourceConnection
-Magento\Framework\Code\Generator::shouldSkipGeneration - type not detected, or class exists
-\Magento\Framework\Code\Generator::createGeneratorInstance -- new for every file
-```
-
-### \Magento\Framework\Code\Generator\EntityAbstract - code generation
-```
-\Magento\Framework\Code\Generator\EntityAbstract::generate
-\Magento\Framework\Code\Generator\EntityAbstract::_validateData - class not existing etc.
-\Magento\Framework\Code\Generator\EntityAbstract::_generateCode
-  - \Magento\Framework\Code\Generator\ClassGenerator extends \Zend\Code\Generator\ClassGenerator
-- \Magento\Framework\Code\Generator\EntityAbstract::_getDefaultConstructorDefinition
-- \Magento\Framework\Code\Generator\EntityAbstract::_getClassProperties
-- \Magento\Framework\Code\Generator\EntityAbstract::_getClassMethods
-```
-
-###### Links
-- [Magento DevDocs - Plugins (Interceptors)](https://devdocs.magento.com/guides/v2.2/extension-dev-guide/plugins.html)
-- [Alan Storm - Magento 2 Object Manager Plugin System](https://alanstorm.com/magento_2_object_manager_plugin_system/)
\ No newline at end of file
diff --git a/1. Magento Architecture and Customization Techniques/6. Configure event observers and scheduled jobs.md b/1. Magento Architecture and Customization Techniques/6. Configure event observers and scheduled jobs.md
deleted file mode 100644
index 2bbc44b..0000000
--- a/1. Magento Architecture and Customization Techniques/6. Configure event observers and scheduled jobs.md	
+++ /dev/null
@@ -1,214 +0,0 @@
-# Configure event observers and scheduled jobs
-
-## Observers
-
-Events are dispatched by modules when certain actions are triggered.
-In addition to its own events, Magento allows you to create your own events that can be dispatched in your code.
-When an event is dispatched, it can pass data to any observers configured to watch that event.
-
-Best practices:
-- Make your observer efficient
-- Do not include business logic
-- Declare observer in the appropriate scope
-- Avoid cyclical event loops
-- Do not rely on invocation order
-
-> 
-> `14. Events`
-> 
-> 14.1. All values (including objects) passed to an event MUST NOT be modified in the event observer. Instead, plugins SHOULD BE used for modifying the input or output of a function.
->
-> -- [Magento DevDocs - Technical guidelines](https://devdocs.magento.com/guides/v2.2/coding-standards/technical-guidelines.html)
-
-
-### Demonstrate how to configure observers
-- can define observer in global area, then disable in specific area
-
-Observers can be configured in the `events.xml` file.
-
-Properties:
-- name (required) - Name of the observer for the event definition
-- instance (required) - Class name of the observer
-- disabled - Is observer active or not (Default: false)
-- shared - Class lifestyle (Default: false)
-
-Example:
-```xml
-<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
-    <event name="cms_block_save_before">
-        <observer name="myObserverName" instance="MyCompany\MyModule\Observer\MyObserver" />
-    </event>
-    <event name="cms_block_save_commit_after">
-        <observer name="myObserverName2" instance="MyCompany\MyModule\Observer\AnotherObserver" disabled="true" shared="true"/>
-    </event>
-</config>
-```
-
-Observer class should be placed in the <module-root>/Observer directory and implement
-[Magento\Framework\Event\ObserverInterface](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Event/ObserverInterface.php)
-interface.
-
-```php
-<?php
-
-class MyObserver implements \Magento\Framework\Event\ObserverInterface
-{
-    public function execute(\Magento\Framework\Event\Observer $observer)
-    {
-        $order = $observer->getEvent()->getData('order'); // $observer->getEvent()->getOrder();
-        // observer code...
-    }
-}
-```
-
-### Dispatching events
-
-Events dispatch by [Magento\Framework\Event\Manager](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Event/Manager.php) class
-that implement [Magento\Framework\Event\ManagerInterface](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Event/ManagerInterface.php) interface:
-> dispatch($eventName, array $data = []);
-
-Example:
-> $this->eventManager->dispatch('cms_page_prepare_save', ['page' => $model, 'request' => $this->getRequest()]);
-
-###### Links
-- [Magento DevDocs - Events and observers](https://devdocs.magento.com/guides/v2.2/extension-dev-guide/events-and-observers.html)
-- [Magento DevDocs - Observers Best Practices](https://devdocs.magento.com/guides/v2.2/ext-best-practices/extension-coding/observers-bp.html)
-
-
-## Scheduled jobs
-
-### Demonstrate how to configure a scheduled job
-
-
-##### Cron groups
-
-A cron group is a logical group that enables you to easily run cron for more than one process at a time. 
-Most Magento modules use the default cron group.
-
-To declare new group and specify settings, create `<module>/etc/cron_groups.xml` file (store view scope):
-
-```xml
-<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Cron:etc/cron_groups.xsd">
-    <group id="default">
-        <schedule_generate_every>15</schedule_generate_every>
-        <schedule_ahead_for>20</schedule_ahead_for>
-        <schedule_lifetime>15</schedule_lifetime>
-        <history_cleanup_every>10</history_cleanup_every>
-        <history_success_lifetime>10080</history_success_lifetime>
-        <history_failure_lifetime>10080</history_failure_lifetime>
-        <use_separate_process>0</use_separate_process>
-    </group>
-</config>
-```
-
-Existing groups:
-- default (no separate process)
-- index - mview, targetrule
-- catalog_event - catalog_event_status_checker - mark event open/closed
-- consumers - consumers_runner if configured to run by cron. `bin/magento queue:consumers:start`. PID file var/{$consumer}.pid
-- staging - staging_apply_version, staging_remove_updates, staging_synchronize_entities_period
-- ddg_automation (dotmailer)
-
-##### crontab.xml
-
-`crontab.xml` file is used to execute an action on schedule.
-This file always located in the <module>/etc/ folder (not in <module>/etc/{area}/)!
-
-```xml
-<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Cron:etc/crontab.xsd">
-    <group id="GROUP_NAME">
-        <job name="CRON_JOB_UNIQUE_ID" instance="CLASS" method="METHOD">
-            <config_path>some/config/path</config_path>
-        </job>
-        <job name="indexer_clean_all_changelogs" instance="Magento\Indexer\Cron\ClearChangelog" method="execute">
-            <schedule>0 * * * *</schedule>
-        </job>
-    </group>
-</config>
-```
-
-run:
-
-- magento cron:run [–group=”"]
-- pub/cron.php?[group=<name>] in a web browser, protect with basic auth
-
-Stack trace:
-```
-\Magento\Cron\Console\Command\CronCommand::execute
-\Magento\Framework\App\Cron::launch
-`default` event
-\Magento\Cron\Observer\ProcessCronQueueObserver
-check for specific group
-cleanup
-generate
-check for standalone process
-```
-
-[\Magento\Cron\Model\Config\Data](https://github.com/magento/magento2/blob/2.3/app/code/Magento/Cron/Model/Config/Data.php) extends [\Magento\Framework\Config\Data](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Config/Data.php)
-- merges [\Magento\Cron\Model\Config\Reader\Db::get](https://github.com/magento/magento2/blob/2.3/app/code/Magento/Cron/Model/Config/Reader/Db.php#L51) from Database
-
-  Sample DB structure:
-```
-default/crontab/GROUP/jobs/JOB/schedule/cron_expr = '* * * * *'
-default/crontab/GROUP/jobs/JOB/schedule/config_path = 'some/config/path' -- try to read schedule from this config, store view scope
-default/crontab/GROUP/jobs/JOB/run/model = 'class::method'
-```
-DB config usage example: [ProductAlert, system.xml](https://github.com/magento/magento2/blob/2.3/app/code/Magento/ProductAlert/etc/adminhtml/system.xml#L38:L45), [ProductAlert, crontab.xml](https://github.com/magento/magento2/blob/2.3/app/code/Magento/ProductAlert/etc/crontab.xml), backend model: [Magento\Cron\Model\Config\Backend\Product\Alert](https://github.com/magento/magento2/blob/2.3/app/code/Magento/Cron/Model/Config/Backend/Product/Alert.php)
-
-`bin/magento cron:install` example:
-```
-#~ MAGENTO START 4d557a63fe1eac8a2827a4eca020c6bb
-* * * * * /usr/bin/php7.0 /var/www/m22ee/bin/magento cron:run 2>&1 | grep -v "Ran jobs by schedule" >> /var/www/m22ee/var/log/magento.cron.log
-* * * * * /usr/bin/php7.0 /var/www/m22ee/update/cron.php >> /var/www/m22ee/var/log/update.cron.log
-* * * * * /usr/bin/php7.0 /var/www/m22ee/bin/magento setup:cron:run >> /var/www/m22ee/var/log/setup.cron.log
-#~ MAGENTO END 4d557a63fe1eac8a2827a4eca020c6bb
-```
-
-how is separate process ran?
-`bin/magento cron:run --group=NAME --bootstrap=standaloneProcessStarted=1`
-
-what is update/cron.php?
-TODO: find out
-
-what is setup:cron:run?
-TODO: find out
-
-###### Links
-- [Magento DevDocs - Configure a custom cron job and cron group (tutorial)](https://devdocs.magento.com/guides/v2.2/config-guide/cron/custom-cron-tut.html)
-- [Magento DevDocs - Custom cron job and cron group reference](https://devdocs.magento.com/guides/v2.2/config-guide/cron/custom-cron-ref.html)
-
-
-### Identify the function and proper use of automatically available events
-
-Model events [\Magento\Framework\Model\AbstractModel](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Model/AbstractModel.php):
-
-- `model_load_before`, `{$_eventPrefix}_load_before`
-- `model_load_after`, `{$_eventPrefix}_load_after`
-- `model_save_commit_after`, `{$_eventPrefix}_save_commit_after`
-- `model_save_before`, `{$_eventPrefix}_save_before`
-- `model_save_after`, `{$_eventPrefix}_save_after`
-- `model_delete_before`, `{$_eventPrefix}_delete_before`
-- `model_delete_after`, `{$_eventPrefix}_delete_after`
-- `model_delete_commit_after`, `{$_eventPrefix}_delete_commit_after`
-
-Flat collection events [\Magento\Framework\Model\ResourceModel\Db\Collection\AbstractCollection](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Model/ResourceModel/Db/Collection/AbstractCollection.php):
-
-- `core_collection_abstract_load_before`, `{_eventPrefix}_load_before`
-- `core_collection_abstract_load_after`, `{_eventPrefix}_load_after`
-
-only if `_eventPrefix` and `_eventObject` defined: `{prefix}_load_before`, `{prefix}_load_after`
-
-EAV collection events [\Magento\Eav\Model\Entity\Collection\AbstractCollection](https://github.com/magento/magento2/blob/2.3/app/code/Magento/Eav/Model/Entity/Collection/AbstractCollection.php):
-
-- eav_collection_abstract_load_before
-
-[\Magento\Framework\Model\AbstractModel](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Model/AbstractModel.php):
-
-- _eventObject = 'object'
-- _eventPrefix = 'core_abstract', e.g. 'catalog_category'
-- _getEventData() - 'data_object' + $_eventObject
-- `model_load_before` (object, field=null, value=ID)
-- `{_eventPrefix}_load_before`, e.g. `catalog_category_load_before` (object, field, value, data_object, category)
-
-###### Links
-- [Cyrill Schumacher's Blog - List of all dispatched events](https://cyrillschumacher.com/magento-2.2-list-of-all-dispatched-events/)
diff --git a/1. Magento Architecture and Customization Techniques/7. Utilize the CLI.md b/1. Magento Architecture and Customization Techniques/7. Utilize the CLI.md
deleted file mode 100644
index 0738dae..0000000
--- a/1. Magento Architecture and Customization Techniques/7. Utilize the CLI.md	
+++ /dev/null
@@ -1,122 +0,0 @@
-# Utilize the CLI
-
-### Describe the usage of bin/magento commands in the development cycle.
-
-### Demonstrate an ability to create a deployment process.
-Modes: *default*, *developer*, *production*. MAGE-MODE env variable
-
-Commands:
-
-- `bin/magento deploy:mode:show`
-- `magento deploy:mode:set {mode} [-s|--skip-compilation]` -- skip compilation when changing to production
-
-cannot switch to default mode, only developer or production
-
-Default:
-
-- errors logged in var/report, not displayed
-- static created dynamically - copied! changes not visible. cached
-
-Developer:
-
-- exceptions displayed, not logged
-- exception thrown if bad event subscriber.
-- var/report detailed
-- static created dynamically - symlinked???, changes visible immediately
-- error handler - throws exception instead of logging (notice etc.)
-
-Production - max speed, no errors, no file generation:
-
-- admin can't enable/disable cache types
-- errors logged, not displayed
-- static not created dynamically, must be deployed
-- not need for www-data to write, pub/static can be read-only
-
-### Commands explaination
-#### setup:di:compile
-1. [Code compilation includes the following (in no particular order):](https://devdocs.magento.com/guides/v2.2/config-guide/cli/config-cli-subcommands-compiler.html)
-* Application code generation (factories, proxies)
-* Area configuration aggregation (optimized dependency injection configurations per area)
-
-   see [generated/metadata](https://devdocs.magento.com/guides/v2.3/extension-dev-guide/code-generation.html#codegen-om)
-* Interceptor generation (optimized code generation of interceptors)
-* Interception cache generation
-* Repositories code generation (generated code for APIs)
-* Service data attributes generation (generated extension classes for data objects)
-* [Running setup:di:compile places the app into a special mode](https://www.cadence-labs.com/2017/07/magento-2-run-setupdicompile/) 
-
-### How to add CLI commands (off-topic)
-
-Magento 2 CLI is based on the Symfony Console component.
-
-To create new CLI command you need:
-- Create command class (the recommended location is {module}/Console/Command)
-This class must extends from [\Symfony\Component\Console\Command\Command](https://github.com/symfony/console/blob/master/Command/Command.php) and have 2 methods:
-
-`configure` -  to set the name, description, command line arguments etc
-
-`execute` - is the place where you write your code
-
-```php
-<?php
-namespace Vendor\Module\Console\Command;
-
-use Symfony\Component\Console\Input\InputArgument;
-use Symfony\Component\Console\Input\InputOption;
-
-class ExampleCommand extends \Symfony\Component\Console\Command\Command
-{
-    protected function configure()
-    {
-        $this->setName('example:hello')
-            ->setDescription('Hello world command');
-        
-        // Positional argument
-        $this->addArgument(
-            'myargument',
-            InputArgument::REQUIRED,
-            'Positional required argument example'
-        );
-        
-        // Not required option
-        $this->addOption(
-            'myoption',
-            null,
-            InputOption::VALUE_OPTIONAL,
-            'Option example',
-            ScopeConfigInterface::SCOPE_TYPE_DEFAULT
-        );
-        
-        parent::configure();
-    }
-
-    protected function execute(\Symfony\Component\Console\Input\InputInterface $input, \Symfony\Component\Console\Output\OutputInterface $output)
-    {
-        $output->writeln('hello world');
-    }
-}
-```
-
-- Declare your command in [\Magento\Framework\Console\CommandListInterface](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Console/CommandListInterface.php) using dependency injection ({module}/etc/di.xml).
-See also CommandListInterface implementation: [\Magento\Framework\Console\CommandList](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Console/CommandList.php)
-
-{module}/etc/di.xml:
-```xml
-<type name="Magento\Framework\Console\CommandListInterface">
-    <arguments>
-        <argument name="commands" xsi:type="array">
-            <item name="exampleHello" xsi:type="object">Vendor\Module\Console\Command\ExampleCommand</item>
-        </argument>
-    </arguments>
-</type>
-```
-
-- Clean the cache and compiled code directories
-
-rm -rf cache/* page_cache/* di/* generation/*
-
-###### Links
-- [Magento DevDocs - How to add CLI commands](https://devdocs.magento.com/guides/v2.2/extension-dev-guide/cli-cmds/cli-howto.html)
-- [Magento DevDocs - Command naming guidelines](https://devdocs.magento.com/guides/v2.2/extension-dev-guide/cli-cmds/cli-naming-guidelines.html)
-- [Symfony Documentation - The Console Component](https://symfony.com/doc/3.4/components/console.html)
-- [Magento - sample-module-command](https://github.com/magento/magento2-samples/tree/master/sample-module-command)
diff --git a/1. Magento Architecture and Customization Techniques/8. Demonstrate the ability to manage the cache.md b/1. Magento Architecture and Customization Techniques/8. Demonstrate the ability to manage the cache.md
deleted file mode 100644
index 7882399..0000000
--- a/1. Magento Architecture and Customization Techniques/8. Demonstrate the ability to manage the cache.md	
+++ /dev/null
@@ -1,170 +0,0 @@
-# Demonstrate the ability to manage the cache
-
-### Describe cache types and the tools used to manage caches.
-
-- config
-- layout
-- block_html
-- collections
-- db_ddl
-- eav
-- full_page
-- reflection
-- translate
-- config_integration
-- config_integration_api
-- config_webservice
-
-Description for most cache type can be found on the [Magento DevDocs - Manage the cache](https://devdocs.magento.com/guides/v2.2/config-guide/cli/config-cli-subcommands-cache.html#config-cli-subcommands-cache-clean-over)
-
-Commands:
-
-- `magento setup:db-schema:upgrade`
-- `magento cache:status`, `magento cache:enable`, `magento cache:disable`
-- `magento cache:clean`, `magento cache:flush`
-
-### Init:
-
-frontend:
-```
-\Magento\Framework\App\ObjectManager\ConfigLoader::load
-cacheType = config, frontend = default
-\Magento\Framework\App\Cache\Frontend\Pool::_initialize
-\Magento\Framework\App\Cache\Frontend\Factory::create
-\Zend_Cache::_makeFrontend
-\Zend_Cache_Core::__construct
-```
-
-backend:
-
-- \Zend_Cache_Backend
-- \Zend_Cache_Backend_File
-- \Magento\Framework\Cache\Backend\Database
-
-How do you add dynamic content to pages served from the full page cache?
-
-1. Mark any block `cacheable="false"` in layout xml - whole page is uncacheable. Example -checkout
-1. Disable caching in controller using *headers*:
-`$page->setHeader('Cache-Control', 'no-store, no-cache, must-revalidate, max-age=0', true);`
-1. Marking block property isScopePrivate - will be loaded via AJAX - deprecated
-1. ESI when Varnish enabled, set TTL - Example - menu block
-1. Configure page variations - extend *http context*, more cached versions of same page - store view, customer group, language, currency, is logged in
-`\Magento\Framework\App\Http\Context::getVaryString`
-
-Only _GET_ and _HEAD_ are cached
-
-Clear cache
-\Magento\Framework\DataObject\IdentityInterface
-
-### when giving product page, must somehow send varnish tags
-Any block can implement IdentityInterface. After rendering layout and before sending output,
-all blocks are examined for implementing this interface. Cache tags are collected as merge of all blocks
-getIdentities() tags.
-
-```
-\Magento\PageCache\Model\Layout\LayoutPlugin::afterGetOutput
-  X-Magento-Tags = merge(all blocks.getIdentities)
-```
-
-block ListProduct:
-
-- every product[].getIdentities
-    - cat_p_{productId}
-    - *if changed categories* - cat_p_c_{categoryId}
-    - *if changed status* - every category[]  cat_p_c_{categoryId}
-    - *if frontend* - 'cat_p'
-- cat_c_p_{categoryId}
-
-block product/view:
-
-- \Magento\Catalog\Model\Product::getIdentities:
-    - cat_p_{productId}
-    - *if changed categories* - cat_p_c_{categoryId}
-    - *if changed status* - every category[]  cat_p_c_{categoryId}
-    - *if frontend* - 'cat_p'
-- *if current_category* - cat_c_{categoryId}
-
-### after reindex, must somehow clean cache
-
-- any indexer.execute -- by MView
-- any indexer.executeFull
-- \Magento\Framework\Indexer\CacheContext::registerTags
-
-plugin \Magento\Indexer\Model\Processor:
-
-\Magento\Indexer\Model\Processor\CleanCache::afterUpdateMview
-
-- event `clean_cache_after_reindex`
-- clean cache cacheContext->getIdentities()
-
-\Magento\Indexer\Model\Processor\CleanCache::afterReindexAllInvalid
-
-- event `clean_cache_by_tags`
-- clean cache cacheContext->getIdentities()
-
-module-cache-invalidate observer `clean_cache_after_reindex`
-\Magento\CacheInvalidate\Observer\InvalidateVarnishObserver::execute
-\Magento\CacheInvalidate\Model\PurgeCache::sendPurgeRequest
-
-### Describe how to operate with cache clearing.
-
-How would you clean the cache? In which case would you refresh cache/flash cache storage?
-
-> To purge out-of-date items from the cache, you can clean or flush cache types:
->
-> - Cleaning a cache type deletes all items from enabled Magento cache types only. In other words, this option does not affect other processes or applications because it cleans only the cache that Magento uses.
-> 
->   Disabled cache types are not cleaned.
->
-> - Flushing a cache type purges the cache storage, which might affect other processes applications that are using the same storage.
->
-> Flush cache types if you’ve already tried cleaning the cache and you’re still having issues that you cannot isolate.
->
-> -- [Magento DevDocs - Manage the cache](https://devdocs.magento.com/guides/v2.2/config-guide/cli/config-cli-subcommands-cache.html#config-cli-subcommands-cache-clean-over)
-
-Sessions and caching data should never be stored in one database in Redis. In that case you'll not have problems with flushing the cache.
-
-### Describe how to clear the cache programmatically.
-
-To clear the cache programmatically you neeed to call next the methods:
-- [\Magento\Framework\App\CacheInterface::remove($identifier)](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/App/CacheInterface.php#L48) - remove cached data by identifier
-- [\Magento\Framework\App\CacheInterface::clean($tags = [])](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/App/CacheInterface.php#L56) - clean cached data by specific tag
-
-##### What mechanisms are available for clearing all or part of the cache?
-
-Dispatch a `clean_cache_by_tags` event with parameter of the object you want to clear from the cache.
-
-Example: [\Magento\Framework\Model\AbstractModel](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Model/AbstractModel.php#L817) (afterSave, afterDelete methods)
-
-```php
-<?php
-public function afterSave()
-{
-    $this->cleanModelCache();
-    $this->_eventManager->dispatch('model_save_after', ['object' => $this]);
-    $this->_eventManager->dispatch('clean_cache_by_tags', ['object' => $this]);
-    $this->_eventManager->dispatch($this->_eventPrefix . '_save_after', $this->_getEventData());
-    $this->updateStoredData();
-    return $this;
-}
-
-public function cleanModelCache()
-{
-    $tags = $this->getCacheTags();
-    if ($tags !== false) {
-        $this->_cacheManager->clean($tags); // \Magento\Framework\App\CacheInterface
-    }
-    return $this;
-}
-```
-
-Default `clean_cache_by_tags` event observers are: 
-- [Magento\PageCache\Observer\FlushCacheByTags](https://github.com/magento/magento2/blob/2.3/app/code/Magento/PageCache/Observer/FlushCacheByTags.php#L57) - if Built-In caching is enabled 
-- [Magento\CacheInvalidate\Observer\InvalidateVarnishObserver](https://github.com/magento/magento2/blob/2.3/app/code/Magento/CacheInvalidate/Observer/InvalidateVarnishObserver.php#L50)- if Varnish caching is enabled
-
-###### Links
-- [Magento DevDocs - Magento cache overview](https://devdocs.magento.com/guides/v2.2/frontend-dev-guide/cache_for_frontdevs.html)
-- [Magento DevDocs - Configure caching](https://devdocs.magento.com/guides/v2.2/config-guide/cache.html)
-- [Magento DevDocs - Partial caching](https://devdocs.magento.com/guides/v2.2/extension-dev-guide/cache/partial-caching.html)
-- [Magento DevDocs - Full Page caching](https://devdocs.magento.com/guides/v2.2/extension-dev-guide/cache/page-caching.html)
-- [Magento DevDocs - Private content](https://devdocs.magento.com/guides/v2.2/extension-dev-guide/cache/page-caching/private-content.html)
diff --git a/1. Magento Architecture and Customization Techniques/Magento Architecture and Customization Techniques.md b/1. Magento Architecture and Customization Techniques/Magento Architecture and Customization Techniques.md
deleted file mode 100644
index 5a14299..0000000
--- a/1. Magento Architecture and Customization Techniques/Magento Architecture and Customization Techniques.md	
+++ /dev/null
@@ -1,540 +0,0 @@
-# 1-Magento Architecture and Customization Techniques
-
-## 1.1 Describe Magento’s module-based architecture
-- registration.php
-- composer.json autoload/files[] = "registration.php"
-- at what stage - when including vendor/autoload.php
-- how registered when not in composer - project composer.json autoload/files[] = app/etc/NonComposerComponentRegistration.php
-
-    app/code/*/*/cli_commands.php, registration.php
-    app/design/*/*/*/registration.php
-    app/i18n/*/*/registration.php
-    lib/internal/*/*/registration.php
-    lib/internal/*/*/*/registration.php
-
-pub/index.php
-app/bootstrap.php
-app/autoload.php
-vendor/autoload.php
-vendor/module[]/registration.php -- last step in Composer init
-Magento\Framework\Component\ComponentRegistrar::register(type='module', name='Prince_Productattach', path='/var/www/...')
-
-How do different modules interact with each other?
-- composer require
-- module.xml sequence - hard requirement, affects load order
-- DI require instance
-
-What side effects can come from this interaction?
-- error when module is missing or disabled
-- error when injecting missing class
-- (?) null or error when using object manager for missing class
-  ReflectionException - Class MissingClass does not exist
-  objectManager->create() = new $type() or new $type(...args) --> PHP Warning:  Uncaught Error: Class 'MissingClass' not found
-
-## 1.2 Describe Magento’s directory structure
-
-- app/code/Vendor/Module
-- app/design/frontend/VendorName/theme_name_lowercase
-- app/i18n/VendorName/en_US
-- vendor/vendor-name/module-theme-package/
-
-Where are the files containing JavaScript, HTML, and PHP located?
-- view/frontend/web/js
-- view/frontend/requirejs-config.js
-- view/frontend/layout
-- view/frontend/templates
-
-How do you find the files responsible for certain functionality?
-
-## 1.3 Utilize configuration XML and variables scope
-
-Determine how to use configuration files in Magento. Which configuration files correspond to different features and
-functionality?
-
-- acl.xml - resource title, sort
-- adminhtml/rules/payment_{country}.xml - paypal
-- address_formats.xml
-- address_types.xml - format code and title only
-- cache.xml - name, instance - e.g. full_page=Page Cache
-- catalog_attributes.xml - catalog_category, catalog_product, unassignable, used_in_autogeneration, quote_item
-- communication.xml
-- config.xml - defaults
-- crontab.xml - group[], job instance, method, schedule
-- cron_groups.xml
-- di.xml - preference, plugins, virtual type
-- eav_attributes.xml - locked entity attributes (global, unique etc.)
-- email_templates.xml - id label file type module -- view/frontend/email/name.html
-- events.xml - observers, shared, disabled
-- export.xml
-- extension_attributes.xml - for, attribute code, attribute type
-- fieldset.xml
-- import.xml
-- indexer.xml - class, view_id, title, description
-- integration.xml - API resources + pre-configure the integration (After Magento 2.2)
-- integration/api.xml - file defines which API resources the integration has access to(Deprecated in Magento 2.2 and all config are moved in integration.xml)
-- integration/config.xml -  pre-configure the integration, the values cannot be edited from the admin panel ((Deprecated in Magento 2.2 and all config are moved in integration.xml)
-- menu.xml
-- module.xml - version, sequence
-- mview.xml - scheduled updates, subscribe to table changes, indexer model
-- page_types.xml
-- payment.xml - groups, method allow_multiple_address
-- pdf.xml - renders by type (invoice, shipment, creditmemo) and product type
-- product_types.xml - label, model instance, index priority, (?) custom attributes, (!) composable types
-- product_options.xml
-- resources.xml
-- routes.xml - Routes, Frontend name, module and extending routes
-- sales.xml - collectors (quote, order, invoice, credit memo)
-- search_engine.xml - Add custom search  engine
-- search_request.xml - index, dimensions, queries, filters, aggregations, buckets
-- sections.xml - action route placeholder -> invalidate customer sections
-- system.xml - adminhtml config
-- validation.xml - entity, rules, constraints -> class
-- view.xml - vars by module
-- webapi.xml - route, method, service class and method, resources
-- widget.xml - class, email compatible, image, ttl (?), label, description, parameters
-- zip_codes.xml
-
-### \Magento\Framework\Config\Reader\Filesystem, \Magento\Framework\Config\ReaderInterface
-Gets .xsd names from schema locator, gets full .xml file list from file resolver, merges all files, validates, runs converter to get resulting array.
-
-- read(scope)
-  + fileResolver->get(_filename)
-  + merge and validate each file (if mode developer)
-  + validate merged dom
-  + converter->convert(dom) => array
-- _idAttributes, _fileName, _schemaFile (from schemaLocator), _perFileSchema (from schemaLocator), filename (menu.xml)
-- schemaFile from schemaLocator
-
-### \Magento\Catalog\Model\ProductTypes\Config\Converter, \Magento\Framework\Config\ConverterInterface - array in any format
-- convert(\DOMDocument $source)
-
-### \Magento\Framework\Config\SchemaLocatorInterface - full path to .xsd
-- getPerFileSchema - per file before merge
-- getSchema - merged file
-
-### config merger = \Magento\Framework\Config\Dom
-- when merging each file
-  + createConfigMerger|merge
-  + \Magento\Framework\Config\Dom::_initDom(dom, perFileSchema)
-  + \Magento\Framework\Config\Dom::validateDomDocument
-  + $dom->schemaValidate
-- after all merged
-  + \Magento\Framework\Config\Dom::validate(mergedSchema)
-  + \Magento\Framework\Config\Dom::validateDomDocument
-  
-## Sensitive and environment settings
-- shared config app/etc/config.php
-- sensitive or system-specific app/etc/env.php:
-
-```
-    <type name="Magento\Config\Model\Config\TypePool">
-       <arguments>
-          <!-- sensitive config items -->
-          <argument name="sensitive" xsi:type="array">
-             <item name="payment/paypal_express/merchant_id" xsi:type="string">1</item>
-             <!-- keys, password, emails, personally identifiable information -->
-          </argument>
-          <!-- environment specific config items -->
-          <argument name="environment" xsi:type="array">
-             <item name="payment/paypal_express/debug" xsi:type="string">1</item>
-             <!-- URLs, IPs, hosts, modes sandbox/live, email recipients -->
-          </argument>
-       </arguments>
-    </type>
-```
-
-sensitive info doesn't get exported with `bin/magento app:config:dump`. use env. params, e.g.
-`CONFIG__DEFAULT__PAYMENT__TEST__PASWORD` for `payment/test/password`
-
-`bin/magento app:config:dump`:
-
-- system-specific > app/etc/env.php
-- shared > app/etc/config.php
-- sensitive - skipped
-
-`bin/magento config:sensitive:set`:
-
-- writes to app/etc/env.php
-
-## 1.4 Demonstrate how to use dependency injection
-
-```
-    <argument xsi:type="object">{typeName}</argument>
-    <argument xsi:type="object" shared="{shared}">{typeName}</argument>
-
-    <argument xsi:type="string">{strValue}</argument>
-    <argument xsi:type="string" translate="true">{strValue}</argument>
-```
-
-* Initial (app/etc/di.xml)
-* Global (<moduleDir>/etc/di.xml)
-* Area-specific (<moduleDir>/etc/<area>/di.xml)
-
-## 1.5 Demonstrate ability to use plugins
-- can't use before Magento\Framework\Interception\... is initialized
-- *after* plugin has access to *arguments*! @since 2.2
-
-```
-    class MyBeautifulClass
-    {
-        use \Magento\Framework\Interception\Interceptor;
-
-        public function __construct($specificArguments1, $someArg2 = null)
-        {
-            $this->___init();
-            parent:__construct($specificArguments1, $someArg2);
-        }
-
-        public function sayHello()
-        {
-            pluginInfo = pluginList->getNext('MyBeautifulClass', 'sayHello')
-            __callPlugins('sayHello', [args], pluginInfo)
-        }
-    }
-```
-
-Magento\Framework\Interception\Interceptor:
-
-- $pluginList = \Magento\Framework\Interception\PluginListInterface
-- $subjectType = 'MyBeautifulClass'
-- `___init` - called in in constructor, pluginList = get from object manager, subjectType = class name
-- pluginList->getNext
-- `___callPlugins`
-- `___callParent`
-
-### how generated?
-
-    \Magento\Framework\App\Bootstrap::create
-    \Magento\Framework\App\Bootstrap::__construct
-    \Magento\Framework\App\ObjectManagerFactory::create
-    \Magento\Framework\ObjectManager\DefinitionFactory::createClassDefinition
-        \Magento\Framework\ObjectManager\DefinitionFactory::getCodeGenerator
-        \Magento\Framework\Code\Generator\Io::__construct
-        \Magento\Framework\Code\Generator::__construct
-        spl_autoload_register([new \Magento\Framework\Code\Generator\Autoloader, 'load']);
-
-    \Magento\Framework\App\ObjectManagerFactory::create
-    \Magento\Framework\Code\Generator::setGeneratedEntities
-    \Magento\Framework\App\ObjectManager\Environment\Developer::configureObjectManager
-
-    \Magento\Framework\Code\Generator\Autoloader::load
-    \Magento\Framework\Code\Generator::generateClass
-
-### Decide how to generate based on file suffix - generator \Magento\Framework\Code\Generator\EntityAbstract
-```
-array (
-  'extensionInterfaceFactory' => '\\Magento\\Framework\\Api\\Code\\Generator\\ExtensionAttributesInterfaceFactoryGenerator',
-  'factory' => '\\Magento\\Framework\\ObjectManager\\Code\\Generator\\Factory',
-  'proxy' => '\\Magento\\Framework\\ObjectManager\\Code\\Generator\\Proxy',
-  'interceptor' => '\\Magento\\Framework\\Interception\\Code\\Generator\\Interceptor',
-  'logger' => '\\Magento\\Framework\\ObjectManager\\Profiler\\Code\\Generator\\Logger',
-    - logs all public methods call
-    - Magento\Framework\ObjectManager\Factory\Log -- missing?
-  'mapper' => '\\Magento\\Framework\\Api\\Code\\Generator\\Mapper',
-    - extractDto() = $this->{$name}Builder->populateWithArray()->create
-  'persistor' => '\\Magento\\Framework\\ObjectManager\\Code\\Generator\\Persistor',
-    - getConnection, loadEntity, registerDelete, registerNew, registerFromArray, doPersist, doPersistEntity
-  'repository' => '\\Magento\\Framework\\ObjectManager\\Code\\Generator\\Repository', -- deprecated
-  'convertor' => '\\Magento\\Framework\\ObjectManager\\Code\\Generator\\Converter',
-    - Extract data object from model
-    - getModel(AbstractExtensibleObject $dataObject) = getProductFactory()->create()->setData($dataObject)->__toArray()
-  'searchResults' => '\\Magento\\Framework\\Api\\Code\\Generator\\SearchResults',
-    - extends \Magento\Framework\Api\SearchResults
-  'extensionInterface' => '\\Magento\\Framework\\Api\\Code\\Generator\\ExtensionAttributesInterfaceGenerator',
-  'extension' => '\\Magento\\Framework\\Api\\Code\\Generator\\ExtensionAttributesGenerator',
-    - extension_attributes.xml
-    - extends \Magento\Framework\Api\AbstractSimpleObject
-    - implements {name}\ExtensionInterface
-    - for every custom attribute, getters and setters
-  'remote' => '\\Magento\\Framework\\MessageQueue\\Code\\Generator\\RemoteServiceGenerator',
-)
-```
-
-```
-Magento\Framework\App\ResourceConnection\Proxy -> type Proxy, name Magento\Framework\App\ResourceConnection
-Magento\Framework\Code\Generator::shouldSkipGeneration - type not detected, or class exists
-\Magento\Framework\Code\Generator::createGeneratorInstance -- new for every file
-```
-
-### \Magento\Framework\Code\Generator\EntityAbstract - code generation
-```
-\Magento\Framework\Code\Generator\EntityAbstract::generate
-\Magento\Framework\Code\Generator\EntityAbstract::_validateData - class not existing etc.
-\Magento\Framework\Code\Generator\EntityAbstract::_generateCode
-  - \Magento\Framework\Code\Generator\ClassGenerator extends \Zend\Code\Generator\ClassGenerator
-- \Magento\Framework\Code\Generator\EntityAbstract::_getDefaultConstructorDefinition
-- \Magento\Framework\Code\Generator\EntityAbstract::_getClassProperties
-- \Magento\Framework\Code\Generator\EntityAbstract::_getClassMethods
-```
-
-
-## 1.6 Configure event observers and scheduled jobs
-
-### Demonstrate how to configure observers
-- can define observer in global area, then disable in specific area
-
-Observer sortOrder:
-
-- before sortOrder=10, before sortOrder=20, before sortOrder=30 ...
-- before and around (first half) called together for same plugin!
-- around (second half) and after called together for same plugin!
-
-Example:
-
-- pluginA.beforeMethod, pluginA.aroundMethod first half
-- pluginB.beforeMethod, pluginB.aroundMethod first half
-- pluginC.beforeMethod, `____________________
-- ____________________, pluginD.aroundMethod first half
-- method()
-- ____________________, pluginD.aroundMethod second half
-- pluginC.afterMethod , ________________________________
-- pluginB.aroundMethod second half, pluginB.afterMethod
-- pluginA.aroundMethod second half, pluginA.afterMethod
-
-### Demonstrate how to configure a scheduled job
-
-cron_groups.xml - store view scope:
-
-- default (no separate process)
-- index - mview, targetrule
-- catalog_event - catalog_event_status_checker - mark event open/closed
-- consumers - consumers_runner if configured to run by cron. `bin/magento queue:consumers:start`. PID file var/{$consumer}.pid
-- staging - staging_apply_version, staging_remove_updates, staging_synchronize_entities_period
-- ddg_automation (dotmailer)
-
-```
-    <group id="NAME">
-        <job name="NAME" instance="CLASS" method="METHOD">
-            <config_path>some/config/path</config_path>
-        </job>
-        <job name="NAME" instance="CLASS" method="METHOD">
-            <schedule>* * * * *</config_path>
-        </job>
-    </group>
-```
-
-run:
-
-- magento cron:run [–group=”"]
-- pub/cron.php?[group=<name>] in a web browser, protect with basic auth
-
-```
-\Magento\Cron\Console\Command\CronCommand::execute
-\Magento\Framework\App\Cron::launch
-`default` event
-\Magento\Cron\Observer\ProcessCronQueueObserver
-check for specific group
-cleanup
-generate
-check for standalone process
-```
-
-`\Magento\Cron\Model\Config\Data` extends `\Magento\Framework\Config\Data`
-- merges \Magento\Cron\Model\Config\Reader\Db::get from Database
-
-  Sample DB structure:
-```
-default/crontab/GROUP/jobs/JOB/schedule/cron_expr = '* * * * *'
-default/crontab/GROUP/jobs/JOB/schedule/config_path = 'some/config/path' -- try to read schedule from this config, store view scope
-default/crontab/GROUP/jobs/JOB/run/model = 'class::method'
-```
-
-
-`bin/magento cron:install` example:
-```
-#~ MAGENTO START 4d557a63fe1eac8a2827a4eca020c6bb
-* * * * * /usr/bin/php7.0 /var/www/m22ee/bin/magento cron:run 2>&1 | grep -v "Ran jobs by schedule" >> /var/www/m22ee/var/log/magento.cron.log
-* * * * * /usr/bin/php7.0 /var/www/m22ee/update/cron.php >> /var/www/m22ee/var/log/update.cron.log
-* * * * * /usr/bin/php7.0 /var/www/m22ee/bin/magento setup:cron:run >> /var/www/m22ee/var/log/setup.cron.log
-#~ MAGENTO END 4d557a63fe1eac8a2827a4eca020c6bb
-```
-
-how is separate process ran?
-`bin/magento cron:run --group=NAME --bootstrap=standaloneProcessStarted=1`
-
-what is update/cron.php?
-TODO: find out
-
-what is setup:cron:run?
-TODO: find out
-
-
-### Identify the function and proper use of automatically available events
-
-Model events \Magento\Framework\Model\AbstractModel:
-
-- `model_load_before`, `{$_eventPrefix}_load_before`
-- `model_load_after`, `{$_eventPrefix}_load_after`
-- `model_save_commit_after`, `{$_eventPrefix}_save_commit_after`
-- `model_save_before`, `{$_eventPrefix}_save_before`
-- `model_save_after`, `{$_eventPrefix}_save_after`
-- `model_delete_before`, `{$_eventPrefix}_delete_before`
-- `model_delete_after`, `{$_eventPrefix}_delete_after`
-- `model_delete_commit_after`, `{$_eventPrefix}_delete_commit_after`
-
-Flat collection events \Magento\Framework\Model\ResourceModel\Db\Collection\AbstractCollection:
-
-- `core_collection_abstract_load_before`, `{_eventPrefix}_load_before`
-- `core_collection_abstract_load_after`, `{_eventPrefix}_load_after`
-
-only if `_eventPrefix` and `_eventObject` defined: `{prefix}_load_before`, `{prefix}_load_after`
-
-EAV collection events \Magento\Eav\Model\Entity\Collection\AbstractCollection:
-
-- eav_collection_abstract_load_before
-
-\Magento\Framework\Model\AbstractModel:
-
-- _eventObject = 'object'
-- _eventPrefix = 'core_abstract', e.g. 'catalog_category'
-- _getEventData() - 'data_object' + $_eventObject
-- `model_load_before` (object, field=null, value=ID)
-- `{_eventPrefix}_load_before`, e.g. `catalog_category_load_before` (object, field, value, data_object, category)
-
-## 1.7 Utilize the CLI
-### Describe the usage of bin/magento commands in the development cycle.
-
-### Demonstrate an ability to create a deployment process.
-Modes: *default*, *developer*, *production*. MAGE-MODE env variable
-
-Commands:
-
-- `bin/magento deploy:mode:show`
-- `magento deploy:mode:set {mode} [-s|--skip-compilation]` -- skip compilation when changing to production
-
-cannot switch to default mode, only developer or production
-
-Default:
-
-- errors logged in var/report, not displayed
-- static created dynamically - copied! changes not visible. cached
-
-Developer:
-
-- exceptions displayed, not logged
-- exception thrown if bad event subscriber.
-- var/report detailed
-- static created dynamically - symlinked???, changes visible immediately
-- error handler - throws exception instead of logging (notice etc.)
-
-Production - max speed, no errors, no file generation:
-
-- admin can't enable/disable cache types
-- errors logged, not displayed
-- static not created dynamically, must be deployed
-- not need for www-data to write, pub/static can be read-only
-
-## 1.8 Demonstrate the ability to manage the cache
-
-### Describe cache types and the tools used to manage caches.
-
-- config
-- layout
-- block_html
-- collections
-- db_ddl
-- eav
-- full_page
-- reflection
-- translate
-- config_integration
-- config_integration_api
-- config_webservice
-
-Commands:
-
-- `magento setup:db-schema:upgrade`
-- `magento cache:status`, `magento cache:enable`, `magento cache:disable`
-- `magento cache:clean`, `magento cache:flush`
-
-### Init:
-
-frontend:
-```
-\Magento\Framework\App\ObjectManager\ConfigLoader::load
-cacheType = config, frontend = default
-\Magento\Framework\App\Cache\Frontend\Pool::_initialize
-\Magento\Framework\App\Cache\Frontend\Factory::create
-\Zend_Cache::_makeFrontend
-\Zend_Cache_Core::__construct
-```
-
-backend:
-
-- \Zend_Cache_Backend
-- \Zend_Cache_Backend_File
-- \Magento\Framework\Cache\Backend\Database
-
-How do you add dynamic content to pages served from the full page cache?
-
-1. Mark any block `cacheable="false"` in layout xml - whole page is uncacheable. Example -checkout
-1. Disable caching in controller using *headers*:
-`$page->setHeader('Cache-Control', 'no-store, no-cache, must-revalidate, max-age=0', true);`
-1. Marking block property isScopePrivate - will be loaded via AJAX - deprecated
-1. ESI when Varnish enabled, set TTL - Example - menu block
-1. Configure page variations - extend *http context*, more cached versions of same page - store view, customer group, language, currency, is logged in
-`\Magento\Framework\App\Http\Context::getVaryString`
-
-Only _GET_ and _HEAD_ are cached
-
-Clear cache
-\Magento\Framework\DataObject\IdentityInterface
-
-### when giving product page, must somehow send varnish tags
-Any block can implement IdentityInterface. After rendering layout and before sending output,
-all blocks are examined for implementing this interface. Cache tags are collected as merge of all blocks
-getIdentities() tags.
-
-```
-\Magento\PageCache\Model\Layout\LayoutPlugin::afterGetOutput
-  X-Magento-Tags = merge(all blocks.getIdentities)
-```
-
-block ListProduct:
-
-- every product[].getIdentities
-    - cat_p_{productId}
-    - *if changed categories* - cat_p_c_{categoryId}
-    - *if changed status* - every category[]  cat_p_c_{categoryId}
-    - *if frontend* - 'cat_p'
-- cat_c_p_{categoryId}
-
-block product/view:
-
-- \Magento\Catalog\Model\Product::getIdentities:
-    - cat_p_{productId}
-    - *if changed categories* - cat_p_c_{categoryId}
-    - *if changed status* - every category[]  cat_p_c_{categoryId}
-    - *if frontend* - 'cat_p'
-- *if current_category* - cat_c_{categoryId}
-
-### after reindex, must somehow clean cache
-
-- any indexer.execute -- by MView
-- any indexer.executeFull
-- \Magento\Framework\Indexer\CacheContext::registerTags
-
-plugin \Magento\Indexer\Model\Processor:
-
-\Magento\Indexer\Model\Processor\CleanCache::afterUpdateMview
-
-- event `clean_cache_after_reindex`
-- clean cache cacheContext->getIdentities()
-
-\Magento\Indexer\Model\Processor\CleanCache::afterReindexAllInvalid
-
-- event `clean_cache_by_tags`
-- clean cache cacheContext->getIdentities()
-
-module-cache-invalidate observer `clean_cache_after_reindex`
-\Magento\CacheInvalidate\Observer\InvalidateVarnishObserver::execute
-\Magento\CacheInvalidate\Model\PurgeCache::sendPurgeRequest
-
-### Describe how to operate with cache clearing.
-
-How would you clean the cache? In which case would you refresh cache/flash cache storage?
-
-
-### Describe how to clear the cache programmatically.
-
-What mechanisms are available for clearing all or part of the cache?
diff --git a/1.Magento-Architecture-Customisation-Techniques.md b/1.Magento-Architecture-Customisation-Techniques.md
new file mode 100755
index 0000000..e619ac4
--- /dev/null
+++ b/1.Magento-Architecture-Customisation-Techniques.md
@@ -0,0 +1,1566 @@
+
+1 - Magento Architecture & Customisation Techniques
+===================================================
+
+1.0 What is a module?
+---------------------
+
+### Magento module overview
+
+> A module is a logical group - that is, a directory containing
+> blocks, controllers, helpers, models - that are related to a specific business feature. In
+> keeping with Magento's commitment to optimal modularity, a module encapsulates one
+> feature and has minimal dependencies on other modules.
+>
+> Modules and themes are the
+> units of customization in Magento. Modules provide business features, with supporting logic,
+> while themes strongly influence user experience and storefront appearance. Both components
+> have a life cycle that allows them to be installed, deleted, and disabled. From the
+> perspective of both merchants and extension developers, modules are the central unit of
+> Magento organization.
+>
+> The Magento Framework provides a set of core logic: PHP code,
+> libraries, and the basic functions that are inherited by the modules and other
+> components
+
+> Magento 2’s module-based architecture keeps that module’s files in one folder. This makes discovery of the functionality pertaining to that module easier.Modules live in one of two places:
+>
+>  • `app/code/MyVendor/MyModule`
+>
+>  • `vendor/vendor-name/module-name`
+
+
+1.1 Describe Magento's module-based architecture
+------------------------------------------------
+
+
+
+Magento 2 modules are realised with MVVM architecture:
+
+
+
+![](./images/Magento-2-Certified-Professional-Developer-Guide-Screenshot-MVC.jpg)
+
+
+MVVM has three layers:
+
+1.  Model - The Model contains the
+            application's business logic and depends on an associated class—the
+            ResourceModel – for database access. Models depend on service contracts to
+            disclose their functionality to other application layers.
+2.  View - The View is both
+            structure and layout of what is seen on a screen – the actual HTML. This is
+            achieved in the PHTML files distributed with modules. Such files are associated with
+            each ViewModel in the Layout XML files, sometimes referred to as binders. The layout
+            files can as well assign JavaScript files to be used on the final page.
+3.  ViewModel -The ViewModel works
+            together with the Model layer and exposes only necessary information to the View layer.
+            In Magento 2, this is handled by the module's Block classes. Note that this was
+            usually part of the Controller role of an MVC system. On MVVM, the controller is only
+            responsible for handling the user flow, meaning that it receives requests and either
+            tells the system to render a view or to redirect the user to another route.
+
+
+
+
+
+![](./images/Magento-2-Certified-Professional-Developer-Guide-Persistence-Layer.jpg)
+
+
+
+Magento 2 architecture consists of 4 layers:
+
+1.  Presentation Layer - Presentation Layer is the top layer that contains view elements
+            (layouts, blocks, templates) and controllers.
+Presentation Layer usually calls the
+            service layer using service contracts. But, depending on the implementation, it may
+            cross over with the business logic.
+2.  Service Layer - Service layer is the layer between presentation and domain layers.
+            It executes service contracts, which are implemented as PHP interfaces. Service
+            contracts allow you to add or change the business logic resource model using the
+            dependency injection file (di.xml). The service layer is also used to provide API access
+            (REST / SOAP or other modules). The service interface is declared in the / API namespace
+            of the module.
+Data (entity) interface is declared inside / Api / Data. Data
+            entities are the structures of data passed to and returned from service
+            interfaces.
+3.  Domain Layer - The domain layer is responsible for business logic that does not
+            contain information about resources and the database. Also, the domain layer may include
+            the implementation of service contracts. Each data model at the domain layer level
+            depends on the resource model, which is responsible for the database access.
+4.  Persistence Layer - The persistence layer describes a resource model that is responsible
+            for retrieving and modifying data in a database using CRUD requests.
+It also
+            implements additional features of business logic, such as data validation and the
+            implementation of database functions.
+
+
+
+
+![Magento Question](./images/icon-question.png)**Describe Module Registration**
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)How to register a Module - registration.php
+
+
+```php
+<?php
+use Magento\Framework\Component\ComponentRegistrar;
+
+ComponentRegistrar::register(
+    ComponentRegistrar::MODULE,
+    '<MY_VENDOR>\<MY_MODULE>',
+    __DIR__
+);
+```
+
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)How to register a Language Package - registration.php
+
+
+```php
+<?php
+
+use Magento\Framework\Component\ComponentRegistrar;
+
+ComponentRegistrar::register(
+    ComponentRegistrar::LANGUAGE,
+    '<MY_VENDOR>\<MY_PACKAGE>',
+    __DIR__
+);
+
+```
+
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)How to register a Theme - registration.php
+
+```php
+<?php
+
+use Magento\Framework\Component\ComponentRegistrar;
+    ComponentRegistrar::register(ComponentRegistrar::THEME,
+    '<MY_AREA>/<MY_VENDOR>/<MY_THEME>',
+    __DIR__
+);
+```
+
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)Register using composer.json autoload/files[] = "registration.php"
+
+
+```json
+{
+    "name": "<MY_VENDOR>/<MY_MODULE>",
+    "autoload": {
+        "psr-4": {
+            "MY\MODULE\": ""
+        },
+        "files": [
+            "registration.php"
+        ]
+    }
+}
+```
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)registration.php search paths
+
+Magento searches the following paths for registration:
+
+*   app/code/*/*/cli_commands.php,registration.php
+*   app/design/*/*/*/registration.php
+*   app/i18n/*/*/registration.php
+*   lib/internal/*/*/registration.php
+*   lib/internal/*/*/*/registration.php
+
+![Magento Question](./images/icon-question.png)**What stage does registration occur?**
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)In composer - vendor/autoload.php:
+
+
+```json
+"autoload": {
+    "files": [
+        "app/etc/NonComposerComponentRegistration.php"
+    ],
+}
+```
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)Not in composer - app/etc/NonComposerComponentRegistration.php:
+
+
+```php
+<?php
+
+use Magento\Framework\Component\ComponentRegistrar;
+
+ComponentRegistrar::register(
+    ComponentRegistrar::MODULE,
+    'Magento_Backend',
+    __DIR__
+);
+```
+
+![Magento Question](./images/icon-question.png)**Describe module limitations? What side effects can come from this Interaction?**
+
+Minimization of software dependencies is a cornerstone of Magento architecture. Based on this principle there are several logical limitations:
+
+*   One module is responsible only for one feature.
+*   Module dependencies on other modules must be declared
+            explicitly.
+*   Excluding or disabling a module should not disable another
+            module.
+*   Not all classes can be overridden with modules.
+
+
+![Magento Question](./images/icon-question.png)**How do different modules interact with each other?**
+
+
+
+Magento 2 is PSR-4 compliant. As a main principle of module
+                            interaction Magento 2 declares a [Dependency Injection](#h.9ofwnl5q9fnf) pattern and [Service
+                                Contracts](https://devdocs.magento.com/guides/v2.3/extension-dev-guide/service-contracts/service-contracts.html&sa=D&ust=1609223264432000&usg=AOvVaw3Ed4_xgfeNaY3n4LjKlqbi).
+
+
+
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)Service Contracts
+
+
+
+Magento 2 is PSR-4 compliant. As a main principle of module
+                            interaction Magento 2 declares a dependency injection pattern and [Service
+                                Contracts](https://devdocs.magento.com/guides/v2.3/extension-dev-guide/service-contracts/service-contracts.html&sa=D&ust=1609223264433000&usg=AOvVaw3FCs8IA6_CgCxPpmLJc36B). At the most basic level they are sets of PHP
+                            interfaces that define certain elements of a module. The Service Contract approach has a lot
+                            of benefits:
+
+
+
+
+
+*   Easy to switch concrete implementation (this is done by setting
+    a preference for the interface in the dependency injection configuration files
+    etc/di.xml)
+*   Consistency over versions
+*   Clear public API of the classes
+*   Easier unit testing
+
+
+
+
+
+![Magento Exam Notes - More information](./images/icon-info.png)It's important to know what a Service Contract is and how it interacts with other modules. A Service Contract is a design pattern consisting of a set of PHP interfaces that are defined for a module, typically in the `<module_dir>/Data` directory which would house your Data Interfaces.
+
+![Magento Exam Notes - More information](./images/icon-info.png)Data Interfaces define functions that return information about data entities such as search results, set validation rules and return validation results. You must define the data interfaces for a service contract in the Api/Data subdirectory of a module e.g. Customer module are in the app/code/Magento/Customer/Api/Data subdirectory.
+
+[More info here](https://devdocs.magento.com/guides/v2.3/extension-dev-guide/service-contracts/design-patterns.html&sa=D&ust=1609223264435000&usg=AOvVaw2RT5AqHcc9eKc9fF2vhFDt).
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)Area Scope
+
+
+
+One of the important parts of module interaction is a Magento area.
+                            All components operate with the system and other components in the scope of default areas.
+
+
+
+Magento has 5 areas types:
+
+| Area code | Entry point | Directory path |Details
+| --- | --- | --- | --- |
+| `adminhtml` | `index.php` or `pub/index.php` | `<theme_dir>/app/design/adminhtml` | Code for components you'll see while working in the Admin panel |
+| `frontend` | `index.php` or `pub/index.php` |  `<theme_dir>/app/design/frontend` | The storefront (or frontend) contains template and layout files that define the appearance of your storefront |
+| `base` | `index.php` or `pub/index.php` | `<theme_dir>/app/design/base` OR `<theme_dir>/Magento_Checkout/layout/override/base/` | Used as a fallback for files absent in adminhtml and frontend areas |
+| `crontab` | `cron.php` | `cron.php` | CRON schedule tasks |
+| `webapi_rest` |  `index.php` or `pub/index.php` | `https://<magento.host>/rest/V1/products/:sku` |  The REST area has a front controller that understands how to do URL lookups for REST-based URLs |
+| `webapi_soap` | `index.php` or `pub/index.php` | WSDL: `https://<magento.host>/soap/<optional_store_code>?wsdl&services=<service_name_1>,<service_name_2>`| The XML SOAP area for API returning SOAP format. |
+| `graphql` | `index.php` or `pub/index.php` | `https://<magento.host>/graphql` | An alternative to REST and SOAP web APIs for frontend development Mainly used for B2C use cases including: Reorders, Inventory Management store pickups, Order history for logged in customers, Replace product-specific mutations that add, products to a cart with a single mutation that can handle all product types, Gift wrapping and messages, Saved payment methods |
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)Module dependencies
+
+
+
+Modules can contain dependencies upon these software components:
+
+*   Other Magento modules.
+*   PHP extensions.
+*   Third party libraries.
+
+
+
+
+
+1.2 Describe Magento's directory structure
+------------------------------------------
+
+![Magento Question](./images/icon-question.png)**Determine how to locate different types of files in Magento. Where are the files containing JavaScript, HTML, and PHP located?**
+
+* `view/{area}/web/js`
+* `view/{area}/web/template`
+* `view/{area}/web/css`
+* `view/{area}/requirejs-config.js`
+* `view/{area}/layout`
+* `view/{area}/templates`
+* `lib/` - Some supporting JS and CSS files are found here.
+
+> **Where**
+>
+> * `{area}` = Application Area code e.g. `frontend` or `adminhtml`
+
+
+![Magento Question](./images/icon-question.png)**How do you find the files responsible for certain functionality?**
+
+Common directories of a module:
+
+
+
+* `Api` - The /Api folder stores the contracts for modules that contain specific actions that can be reliably utilized from various places in the app.
+    * `Api/Data` - This folder contains interfaces that represent data. Examples of this would be a Product interface, a Category interface or a Customer interface. The concrete implementations of these interfaces usually do little more than provide getters and setters for data (a.k.a Data Transfer Objects).
+* `Block` - PHP view
+                            classes as part of Model View Controller(MVC) vertical implementation of module
+                            logic.
+* `Console` - Console CLI
+                            commands
+* `Controller` - PHP
+                            controller classes as part of MVC vertical implementation of module logic.
+    * `Controller/Adminhtml` - Admin
+                            controllersCron - Cron job
+                            classes
+* `Cron` - This folder is the standard place for storing actions that are executed on a schedule (cron job).
+* `etc` - Configuration
+                            files; in particular, `module.xml`, which is required.
+* `Helper` - Helpers
+* `i18n` - Localization files in CSV format (languages)
+* `Model` - PHP model classes as part of MVC
+                            vertical implementation of module logic.
+    * `Model/ResourceModel` - Database
+                            interactionsObserver - Event
+                            listeners
+* `Observer` - Event Listeners. When Magento fires an event, listeners that are attached to it are called. This decouples the system.
+* `Plugin` - Contains any
+                            needed plug-ins.
+* `Setup` -
+                            Classes for module database structure and data setup which are invoked when installing or
+                            upgrading.
+* `Test` - Unit Tests
+                            tests
+* `Ui` - UI component
+                            classes, forms, grid etc
+* `view` - View files, including static view files, design templates, email
+                            templates, and layout files:
+  * `view/{area}/email`
+  * `view/{area}/layout`
+  * `view/{area}/templates`
+  * `view/{area}/ui_component`
+  * `view/{area}/ui_component/templates`
+  * `view/{area}/web`
+  * `view/{area}/web/template`
+  * `view/{area}/requirejs-config.js`
+
+
+
+
+![Magento Exam Notes - More information](./images/icon-info.png)You do not have to memorise all this, the important thing to understand is that when you are produced a file or directory name, you understand what it's purpose is for.
+
+* Magento root app directory location `<magento_install_dir>/app`:
+
+* Modules - `app/code`.
+
+* Storefront themes - `app/design/frontend`.
+
+* Admin themes - `app/design/adminhtml`.
+
+* Language packages - use `app/i18n`.
+
+* Or (via composer): `<magento_install_dir>/vendor`
+
+
+![Magento Question](./images/icon-question.png)**What files are required when creating a module?**
+
+
+
+* `registration.php`: Among other things, this file specifies the directory in which
+                            the component is installed by vendors in production environments. By default, composer
+                            automatically installs components in the /vendor directory. For more information, see
+                            Component registration.
+
+* `etc/module.xml`: This file specifies basic information about the component such
+                            as the components dependencies and its version number. This version number is used to
+                            determine schema and data updates when bin/magento setup:upgrade is
+                            run.
+
+* `composer.json`: Specifies component dependencies and other metadata. For more
+                            information, see Composer integration.
+
+
+
+
+1.3 Utilize configuration XML and variables scope
+-------------------------------------------------
+
+![Magento Question](./images/icon-question.png)**Determine how to use configuration files in Magento. Which configuration files correspond to different features and functionality?**
+
+
+
+* [`acl.xml`](#h.gk6g5dbgvggm) - Restricting menu
+                            actions, resource title, sortadminhtml/rules/payment_{country}.xml -
+                            PayPaladdress_formats.xml
+address_types.xml - format code and title only[cache.xml](#h.d3c5w1uvsp70) - Create custom cache type, name, instance - e.g. full_page=Page
+                            Cachecatalog_attributes.xml - Contains the list of attributes that serve different purposes.
+                            catalog_category, catalog_product, unassignable, used_in_autogeneration, quote_item
+                            *[communication.xml](#h.c0x3qack8ych) - Queue Consumer
+* [`config.xml`](#h.glpavwxvxuhd) - Adminhtml menus default values
+* [`crontab.xml`](#h.nzp3v0np709e) - CRON tasks group[], job instance, method, schedule
+* [`cron_groups.xml`](#h.nzp3v0np709e) - Grouping
+                            / split processes
+* [`di.xml`](#h.9ofwnl5q9fnf) - preferences,
+                            plugins, virtual types
+
+
+
+* [`db_schema.xml`](#h.iqvl9uln4170) - Declarative setup declares what the database structure should
+                            be.
+* [`eav_attributes.xml`](#h.wm8oeat9wvdw) - EAV
+                            attribute configuration: locked entity attributes (global, unique etc.)
+* email_templates.xml - Specifies email templates that are used in Magento. The template id is the concatenated XML-style path to where in system configuration template is specified.
+* [`events.xml`](#h.y2lezqicnwxl) -
+                            Define an Observers: shared, disabled *export.xml - Add new column to exports
+* [`extension_attributes.xml`](#h.15bsya8yrb45) -
+                            Extension attributes, for, attribute code, attribute typefieldset.xml - Magento UI Object copying, e.g.
+                            customer address copy firstname lastname with
+* `import.xml` - same as export but
+                            import
+* [`indexer.xml`](#h.xa0vtkhng9ut) - Create a new
+                            indexer class, view_id, title, description
+* [integration.xml](#h.t252zlddzc3r)
+
+    * [`integration/api.xml`](#h.85qnykcohlui) -
+                            Defines which API resources the integration has access to.
+    * [`integration/config.xml`](#h.pbacdg8dooea) - An
+                            Integrations pre-configured with default values.
+* [`menu.xml`](#h.gk6g5dbgvggm) - Admin main left menu
+* [`module.xml`](#h.n1343l3gk3km) - (required) Defines a module: version, sequence
+* [`mview.xml`](#h.2m5sw7piaq5j) - Indexes, React to MySQLtriggers - scheduled updates, subscribe to
+                            table changes, indexer model
+* `page_types.xml`
+* [`payment.xml`](#h.ctho0c6bcdkk) - Declaring a
+                            new Payment Method: groups, method allow_multiple_addresspdf.xml - renders by type (invoice,
+                            shipment, credit memo) and product typeproduct_types.xml - Create a new product
+                            type. label, model instance, index priority, (?) custom attributes, (!) composable
+                            typesproduct_options.xml
+
+
+
+* [`queue.xml`](https://devdocs.magento.com/guides/v2.4/extension-dev-guide/message-queues/queue-migration.html&sa=D&ust=1609223264462000&usg=AOvVaw3OB1YP_nd35xQiu2i7KxN9) - (deprecated) Old way of defining a new Queue consumer [see
+                                this article](https://devdocs.magento.com/guides/v2.4/extension-dev-guide/message-queues/queue-migration.html&sa=D&ust=1609223264463000&usg=AOvVaw3PMNONHbowdtWoeZa0GGUF) on how to upgrade this.
+
+
+
+* [`queue_consumer.xml`](#h.bokyb17e6arz) - Where we define the consumer parameters. It's also possible to declare a
+                            handler class in this file.
+
+
+
+* [`queue_topology.xml`](#h.qakz6upsjogv) - Defines the message routing rules and declares queues and exchanges.
+
+
+
+* [`queue_publisher.xml`](#h.yx5eensvx7ac) - Send a message to a message bus without knowing who is interested in the
+                            message.
+* `resources.xml`
+* [`routes.xml`](#h.39aby0sbkm32) - Map a Controller to a
+                            Route. Creating a new Router
+                            (when module/action/method doesn't fit).
+* [`sales.xml`](#h.6bmvxvofcj95) - Define totals for entities (quote, order, invoice, credit
+                            memo)search_engine.xml -
+search_request.xml - Elastic search
+                            related: index, dimensions, queries, filters, aggregations, bucketssections.xml - action route placeholder
+                            -> invalidate customer sections
+* [`system.xml`](#h.op69p944prs) - adminhtml menu
+                            system configvalidation.xml - Regex validation entity, rules, constraints ->
+                            classview.xml - vars by
+                            module
+* `view.xml` - Similar to `config.xml` but used for specifying default values for design configuration.
+* [`webapi.xml`](#h.2lcvcwr56aq) - Create new API
+                            route, method, service class and method, resourceswidget.xml - class, email compatible,
+                            image, ttl (?), label, description, parameterszip_codes.xml
+* `widget.xml` - Configures widgets to be used in products, CMS pages, and CMS blocks.
+
+
+
+
+1.4 Demonstrate how to use dependency injection
+-----------------------------------------------
+
+![Magento Question](./images/icon-question.png)**Describe Magento's dependency injection approach and architecture.**
+
+
+> Dependency Injection is a design pattern that allows an object A
+> to declare its dependencies to an external object B that supplies those dependencies. The
+> dependencies declared by A are usually class interfaces and the dependencies B provides are
+> concrete implementations for those interfaces. This allows for loose coupling of code
+> because object A no longer needs to be concerned with initializing its own dependencies.
+> Object B decides which implementations to provide to object A based on a configuration or
+> desired behavior.
+
+
+
+
+![Magento Exam Notes - More information](./images/icon-info.png)This is probably very useful to memorise as this question is more general programming related but also a big part of core Magento 2
+
+![Magento Question](./images/icon-question.png)**Identify how to use DI configuration files for customizing Magento?**
+
+> Magento loads `di.xml` files and merges them all together from the
+                            following stages:
+*   Initial master file (`<magento_install_dir>/app/etc/di.xml`)
+*   Global (`<module_dir>/etc/di.xml`)
+*   Area-specific (`<module_dir>/etc/{area}/di.xml`)
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)Plugins
+> Plugins allow you to wrap another class’ public functions, add a before method to modify the input arguments, or add an after method to modify the output. These will be discussed more in the next section.Example: `vendor/magento/module-catalog/etc/di.xml` (search for “plugins”)
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)Preferences
+> Preferences are used to substitute entire classes. They can also be used to specify a concrete class for an interface. If you create a service contract for a repository in your /Api folder and a concrete class in /Model, you can create a preference like:
+
+```xml
+<preference for="MyVendor\MyModule\Api\PromotionRepositoryInterface" type="MyVendor\MyModule\Model\PromotionRepository" />
+```
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)Virtual Types
+> A virtual type allows the developer to create an instance of an existing class that has custom constructor arguments. This is useful in cases where you need a “new” class only because the constructor arguments need to be changed.This is used frequently in Magento to reduce redundant PHP classes.
+
+Argument Preferences / Constructor Arguments
+> It is possible to modify what objects are injected into specific classes by targeting the name of the argument to associate it with the new class.Now, with Magento 2, you can inject your custom class into any other classes constructor in di.xmlExample:
+
+```xml
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"-xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
+    <type name="MyVendor\ProductPromoter\Algorithms\Primary">
+        <arguments>
+            <argument name="basedOn" xsi:type="string">sort_order</argument>
+        </arguments>
+    </type>
+</config>
+```
+
+![Magento Question](./images/icon-question.png)**How are objects realized in Magento?**
+
+
+
+> They are instantiated via the:
+
+*   Object manager
+*   Arguments via Dependency Injection
+
+
+
+
+
+![Magento Question](./images/icon-question.png)**Where would you set sensitive settings?**
+
+
+
+* Shared config: `app/etc/config.php`
+* Sensitive config:
+                            `app/etc/env.php`
+
+
+
+
+![Magento Question](./images/icon-question.png)**Why is it important to have a centralized process creating object instances?**
+
+> Through the Dependency inversion principle, Using interfaces in
+> your code reduces the risk of incompatibility bugs when Magento changes the underlying
+> implementation of those interfaces. It also avoids the inheritance, which means that
+> applications become more flexible. In this, you don't need to think about the child
+> classes when changing the parent one.
+
+
+
+
+![Magento Exam Notes - More information](./images/icon-info.png)This is probably very useful to memorise as this question is more general programming related but also a big part of Magento 2
+
+![Magento Question](./images/icon-question.png)**How can you override a native class, inject your class into another object, and use other techniques available in di.xml (such as virtualTypes)?**
+
+
+
+Using a DI preference from a custom module:
+
+Preference `di.xml`
+```xml
+<preference for="" type="" />
+```
+
+> For `<virtualType>` Inject your class into another object: use a `<type/>` entry with a `<argument xsi:type="object">\Path\To\Your\Class</argument>` entry in the `<arguments/>` node.
+
+![Magento Exam Notes - More information](./images/icon-info.png)Preferences in the di.xml are very commonly used.
+
+1.5 Demonstrate ability to use plugins
+--------------------------------------
+
+![Magento Question](./images/icon-question.png)**Demonstrate how to design complex solutions using the plugin's life cycle.**
+
+> There are three types of plugins in magento: **around, before and after interceptors**. Classes, abstract classes and interfaces
+> that are implementations of or inherit from classes that have plugins will also inherit plugins from the parent class. For example, if you create a plugin for `Magento\Catalog\Block\Product\AbstractProduct`, plugin methods will be called for all child classes, such as `Magento\Catalog\Block\Product\View`,`Magento\Catalog\Block\Product\ProductList\Upsell` and so on...
+
+
+![Magento Exam Notes - More information](./images/icon-info.png)The important thing to remember here is that plugins' life cycles are based before, around and after the overriding method.
+
+![Magento Exam Notes - More information](./images/icon-info.png)An around plugin should only be when the execution of the before and after plugins must be suppressed.
+
+![Magento Question](./images/icon-question.png)**How do multiple plugins interact, and how can their execution order be controlled?**
+
+> The `sortOrder` property controls how your plugin interacts with other plugins on the same class.
+
+
+![Magento Question](./images/icon-question.png)**How do you debug a plugin if it doesn't work?**
+
+
+
+> Magento automatically generates an Interceptor class for the
+> plugin target and store it in the generated\code directory. If it's not working then
+> this will not have been created in which you may need to compile DI or check the logs for
+> errors.
+
+
+
+
+![Magento Question](./images/icon-question.png)**Identify strengths and weaknesses of plugins. What are the limitations of using plugins for customization? In which cases should plugins be avoided?**
+
+> Plugins only work on public methods for any classes or interfaces. So plugins CANNOT be used on following:
+
+1.  Final methods
+2.  Final classes
+3.  Non-public methods
+4.  Class methods (such as static methods)
+5.  _construct
+6.  Virtual types
+7.  Objects that are instantiated before Magento\Framework\Interception is bootstrapped
+
+
+> Plugins are useful to modify the input, output, or execution of
+> an existing method. Plugins are also best to be avoided in situations where an event
+> observer will work. Events work well when the flow of data does not have to be
+> modified.
+> Around-plugins SHOULD only be used when behavior of an original method is
+> supposed to be substituted in certain scenarios, they increase stack traces and affect
+> performance. Used improperly, an around plugin can prevent the system from functioning. They
+> can also make understanding what is going on by reading source code hard (spooky action at a
+> distance).
+
+
+
+
+![Magento Exam Notes - More information](./images/icon-info.png)Important and useful.
+
+1.6 Configure event observers and scheduled jobs
+------------------------------------------------
+
+### Observers
+
+Events are dispatched by modules when certain actions are triggered. In addition to its own events, Magento allows you to create your own events that can be dispatched in your code. When an event is dispatched, it can pass data to any observers configured to watch that event.
+
+![Magento Question](./images/icon-question.png)**Demonstrate how to configure observers. How do you make your observer only active on the frontend or backend?**
+
+> Observers can be configured in the events.xml file. It can be global and specific to either front-end or back-end. The structure goes as follows within your Module:
+*   `<module>/etc`
+*   `<module>/etc/frontend`
+*   `<module>/etc/adminhtml`
+
+![Magento Exam Notes - More information](./images/icon-info.png)I've seen many questions about events.xml and area codes appear before in the past exam questions
+
+
+
+Observers have the following properties:
+
+*   name (required) - Name of the observer for the event
+            definition
+*   instance (required) - Class name of the observer
+*   disabled - Is observer active or not (Default: false)
+
+*   shared - Class lifestyle (Default: false)
+
+
+Events dispatch by Magento\Framework\Event\Manager class that implement Magento\Framework\Event\ManagerInterface interface:
+```php
+$this->eventManager->dispatch('cms_page_prepare_save', ['page' => $model, 'request' => $this->getRequest()]);
+```
+
+
+### CRONtab
+
+![Magento Question](./images/icon-question.png)**Demonstrate how to configure a scheduled job. Which parameters are used in configuration, and how can configuration interact with server configuration?**
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)CRON group
+
+
+
+> A cron group is a logical group that enables you to easily run cron
+> for more than one process at a time. Most Magento modules use the default cron group. Each
+> group is run on a separate PHP process.
+> To declare new group and specify settings, create `<module>/etc/cron_groups.xml` file (store view scope):
+
+```xml
+<?xml version="1.0"?>
+
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Cron:etc/cron_groups.xsd">
+    <group id="default">
+        <schedule_generate_every>15</schedule_generate_every>
+        <schedule_ahead_for>20</schedule_ahead_for>
+        <schedule_lifetime>15</schedule_lifetime>
+        <history_cleanup_every>10</history_cleanup_every>
+        <history_success_lifetime>10080</history_success_lifetime>
+        <history_failure_lifetime>10080</history_failure_lifetime>
+        <use_separate_process>0</use_separate_process>
+    </group>
+</config>
+```
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)CRON tab
+
+> `crontab.xml` file is used to execute an action on schedule. This file always located in the <module>/etc/
+
+Parameters used:
+
+```xml
+<?xml version="1.0"?>
+
+<config>
+    <group id="default">
+        <job name="indexer_clean_all_changelogs" instance="Magento\Indexer\Cron\ClearChangelog" method="execute">
+            <schedule>0 * * * *</schedule>
+        </job>
+    </group>
+</config>
+```
+
+![Magento Exam Notes - More information](./images/icon-info.png)You won't be expected to write this off-by-heart but it will pay to understand it's required parameters
+
+* `update/cron.php` - NOT used any more since 2.1
+* `bin/magento setup:cron:run` - only used during installation
+* `bin/magento cron:run` [–-group=] - the main cron run command
+* `pub/cron.php` [--group=] in a web browser, protect with basic auth
+* You can also override the schedule times of CRON groups via the admin in: __Admin > Stores > Configuration > Advanced > System > Cron (Scheduled * Tasks)__
+
+
+![Magento Exam Notes - More information](./images/icon-info.png)All the times are in minutes.
+
+![Magento Question](./images/icon-question.png)**Identify the function and proper use of automatically available events, for example *_load_after, etc.**
+
+
+
+Load, Save, Delete on Model, Flat Collections & EAV Collections before + after:
+```
+model_load_before,
+{$_eventPrefix}_load_before
+model_load_after,
+{$_eventPrefix}_load_after
+model_save_commit_after,
+{$_eventPrefix}_save_commit_after
+model_save_before,
+{$_eventPrefix}_save_before
+model_save_after,
+{$_eventPrefix}_save_after
+model_delete_before,
+{$_eventPrefix}_delete_before
+model_delete_after,
+{$_eventPrefix}_delete_after
+model_delete_commit_after,
+{$_eventPrefix}_delete_commit_after
+core_collection_abstract_load_before,
+{_eventPrefix}_load_before
+core_collection_abstract_load_after,
+{_eventPrefix}_load_after
+eav_collection_abstract_load_before
+```
+
+
+
+![Magento Exam Notes - More information](./images/icon-info.png) Just remember that core events such as the above will feature _before and _after suffixes
+
+1.7 Utilize the CLI
+-------------------
+
+![Magento Question](./images/icon-question.png)**Describe the usage of bin/magento commands in the development cycle. Which commands are available?**
+
+`php bin/magento`
+```
+Magento CLI 2.4.2-p1
+
+Usage:
+  command [options] [arguments]
+
+Options:
+  -h, --help            Display this help message
+  -q, --quiet           Do not output any message
+  -V, --version         Display this application version
+      --ansi            Force ANSI output
+      --no-ansi         Disable ANSI output
+  -n, --no-interaction  Do not ask any interactive question
+  -v|vv|vvv, --verbose  Increase the verbosity of messages: 1 for normal output, 2 for more verbose output and 3 for debug
+
+Available commands:
+  help                                                 Display help for a command
+  list                                                 List commands
+ admin
+  admin:user:create                                    Creates an administrator
+  admin:user:unlock                                    Unlock Admin Account
+ app
+  app:config:dump                                      Create dump of application
+  app:config:import                                    Import data from shared configuration files to appropriate data storage
+  app:config:status                                    Checks if config propagation requires update
+ braintree
+  braintree:migrate                                    Migrate stored cards from a Magento 1 database
+ cache
+  cache:clean                                          Cleans cache type(s)
+  cache:disable                                        Disables cache type(s)
+  cache:enable                                         Enables cache type(s)
+  cache:flush                                          Flushes cache storage used by cache type(s)
+  cache:status                                         Checks cache status
+ catalog
+  catalog:images:resize                                Creates resized product images
+  catalog:product:attributes:cleanup                   Removes unused product attributes.
+ cms
+  cms:wysiwyg:restrict                                 Set whether to enforce user HTML content validation or show a warning instead
+ config
+  config:sensitive:set                                 Set sensitive configuration values
+  config:set                                           Change system configuration
+  config:show                                          Shows configuration value for given path. If path is not specified, all saved values will be shown
+ cron
+  cron:install                                         Generates and installs crontab for current user
+  cron:remove                                          Removes tasks from crontab
+  cron:run                                             Runs jobs by schedule
+ customer
+  customer:hash:upgrade                                Upgrade customer's hash according to the latest algorithm
+ deploy
+  deploy:mode:set                                      Set application mode.
+  deploy:mode:show                                     Displays current application mode.
+ dev
+  dev:di:info                                          Provides information on Dependency Injection configuration for the Command.
+  dev:profiler:disable                                 Disable the profiler.
+  dev:profiler:enable                                  Enable the profiler.
+  dev:query-log:disable                                Disable DB query logging
+  dev:query-log:enable                                 Enable DB query logging
+  dev:source-theme:deploy                              Collects and publishes source files for theme.
+  dev:template-hints:disable                           Disable frontend template hints. A cache flush might be required.
+  dev:template-hints:enable                            Enable frontend template hints. A cache flush might be required.
+  dev:template-hints:status                            Show frontend template hints status.
+  dev:tests:run                                        Runs tests
+  dev:urn-catalog:generate                             Generates the catalog of URNs to *.xsd mappings for the IDE to highlight xml.
+  dev:xml:convert                                      Converts XML file using XSL style sheets
+ dotdigital
+  dotdigital:connector:automap                         Auto-map data fields
+  dotdigital:connector:enable                          Add Dotdigital API credentials and enable the connector
+  dotdigital:migrate                                   Migrate data into email_ tables to sync with Engagement Cloud
+  dotdigital:sync                                      Run syncs to populate email_ tables before importing to Engagement Cloud
+  dotdigital:task                                      Run dotdigital module tasks on demand
+ downloadable
+  downloadable:domains:add                             Add domains to the downloadable domains whitelist
+  downloadable:domains:remove                          Remove domains from the downloadable domains whitelist
+  downloadable:domains:show                            Display downloadable domains whitelist
+ encryption
+  encryption:payment-data:update                       Re-encrypts encrypted credit card data with latest encryption cipher.
+ i18n
+  i18n:collect-phrases                                 Discovers phrases in the codebase
+  i18n:pack                                            Saves language package
+  i18n:uninstall                                       Uninstalls language packages
+ indexer
+  indexer:info                                         Shows allowed Indexers
+  indexer:reindex                                      Reindexes Data
+  indexer:reset                                        Resets indexer status to invalid
+  indexer:set-dimensions-mode                          Set Indexer Dimensions Mode
+  indexer:set-mode                                     Sets index mode type
+  indexer:show-dimensions-mode                         Shows Indexer Dimension Mode
+  indexer:show-mode                                    Shows Index Mode
+  indexer:status                                       Shows status of Indexer
+ info
+  info:adminuri                                        Displays the Magento Admin URI
+  info:backups:list                                    Prints list of available backup files
+  info:currency:list                                   Displays the list of available currencies
+  info:dependencies:show-framework                     Shows number of dependencies on Magento framework
+  info:dependencies:show-modules                       Shows number of dependencies between modules
+  info:dependencies:show-modules-circular              Shows number of circular dependencies between modules
+  info:language:list                                   Displays the list of available language locales
+  info:timezone:list                                   Displays the list of available timezones
+  info:unirgy:list-modules                             List installed licenses
+ inventory
+  inventory:reservation:create-compensations           Create reservations by provided compensation arguments
+  inventory:reservation:list-inconsistencies           Show all orders and products with salable quantity inconsistencies
+ inventory-geonames
+  inventory-geonames:import                            Download and import geo names for source selection algorithm
+ maintenance
+  maintenance:allow-ips                                Sets maintenance mode exempt IPs
+  maintenance:disable                                  Disables maintenance mode
+  maintenance:enable                                   Enables maintenance mode
+  maintenance:status                                   Displays maintenance mode status
+ media-content
+  media-content:sync                                   Synchronize content with assets
+ media-gallery
+  media-gallery:sync                                   Synchronize media storage and media assets in the database
+ module
+  module:config:status                                 Checks the modules configuration in the 'app/etc/config.php' file and reports if they are up to date or not
+  module:disable                                       Disables specified modules
+  module:enable                                        Enables specified modules
+  module:status                                        Displays status of modules
+  module:uninstall                                     Uninstalls modules installed by composer
+ newrelic
+  newrelic:create:deploy-marker                        Check the deploy queue for entries and create an appropriate deploy marker.
+ queue
+  queue:consumers:list                                 List of MessageQueue consumers
+  queue:consumers:start                                Start MessageQueue consumer
+ remote-storage
+  remote-storage:sync                                  Synchronize media files with remote storage.
+ sampledata
+  sampledata:deploy                                    Deploy sample data modules for composer-based Magento installations
+  sampledata:remove                                    Remove all sample data packages from composer.json
+  sampledata:reset                                     Reset all sample data modules for re-installation
+ security
+  security:recaptcha:disable-for-user-forgot-password  Disable reCAPTCHA for admin user forgot password form
+  security:recaptcha:disable-for-user-login            Disable reCAPTCHA for admin user login form
+ setup
+  setup:backup                                         Takes backup of Magento Application code base, media and database
+  setup:config:set                                     Creates or modifies the deployment configuration
+  setup:db-data:upgrade                                Installs and upgrades data in the DB
+  setup:db-declaration:generate-patch                  Generate patch and put it in specific folder.
+  setup:db-declaration:generate-whitelist              Generate whitelist of tables and columns that are allowed to be edited by declaration installer
+  setup:db-schema:upgrade                              Installs and upgrades the DB schema
+  setup:db:status                                      Checks if DB schema or data requires upgrade
+  setup:di:compile                                     Generates DI configuration and all missing classes that can be auto-generated
+  setup:install                                        Installs the Magento application
+  setup:performance:generate-fixtures                  Generates fixtures
+  setup:rollback                                       Rolls back Magento Application codebase, media and database
+  setup:static-content:deploy                          Deploys static view files
+  setup:store-config:set                               Installs the store configuration. Deprecated since 2.2.0. Use config:set instead
+  setup:uninstall                                      Uninstalls the Magento application
+  setup:unirgy:add-license                             Add Unirgy license
+  setup:unirgy:check-updates                           Check for module updates
+  setup:unirgy:update-reinstall                        Update - reinstall unirgy modules
+  setup:upgrade                                        Upgrades the Magento application, DB data, and schema
+ store
+  store:list                                           Displays the list of stores
+  store:website:list                                   Displays the list of websites
+ theme
+  theme:uninstall                                      Uninstalls theme
+ varnish
+  varnish:vcl:generate                                 Generates Varnish VCL and echos it to the command line
+ yotpo
+  yotpo:reset                                          Reset Yotpo sync flags &/or configurations
+  yotpo:sync                                           Sync Yotpo manually (reviews module)
+  yotpo:update-metadata                                Manually send platform metadata to Yotpo
+```
+
+> Modes: default, developer, production. MAGE-MODE env variable
+
+```bash
+bin/magento deploy:mode:show
+bin/magento deploy:mode:set {mode} [-s|--skip-compilation]
+```
+
+
+![Magento Exam Notes - More information](./images/icon-info.png)Ambiguous question, there are many commands in bin/magento - this answer assumes the command `bin/magento deploy:mode:show`
+
+![Magento Question](./images/icon-question.png)**How are commands used in the development cycle?**
+
+
+
+> During DI compilation `bin/magento setup:di:compile`. Code compilation includes the following (in no particular order):
+
+*   Application code generation (factories, proxies)
+*   Area configuration aggregation (optimized dependency
+        injection configurations per area) see generated/metadata
+*   Interceptor generation (optimized code generation of
+        interceptors)
+*   Interception cache generation
+*   Repositories code generation (generated code for
+        APIs)
+*   Service data attributes generation (generated extension
+        classes for data objects)
+*   Running setup:di:compile places the app into a special
+        mode
+
+![Magento Question](./images/icon-question.png)**Demonstrate an ability to create a deployment process. How does the application behave in different deployment modes, and how do these behaviors impact the deployment approach for PHP code, frontend assets, etc?**
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)Default mode
+
+* Symlinks are established in the `pub/static` folder. These are linked from files in the `app/code` or `app/design` folders.
+* Exceptions are not displayed to the user (making development very difficult). They are logged in `var/log`.
+* Static files are generated on the fly and are symlinked into the `var/view_preprocessed` folder.
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)Developer mode
+
+* Symlinks are established in the `pub/static` folder. These are linked from files in the `app/code` or `app/design` folders.
+* Errors are shown to the user and logging is verbose. Caution: debug logging is disabled by default even in developer mode.
+* Magento automatically builds code for plugins (interceptors), factories, etc. as it does in the other modes.
+* Slow performance.
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)Production mode
+
+* Max speed, no errors, no file generation: admin can't enable/disable cache types
+* Exceptions are not displayed to the user (making development very difficult). They are logged in `var/log`.
+* Static assets not created dynamically, must be deployed via CLI such like: `php bin/magento setup:static-content:deploy -f en_AU en_US`
+
+
+![](./images/Magento2-Certification-Exam-Notes-Detailed-Insight-Deploy-Modes.png)
+
+![Magento Exam Notes - More information](./images/icon-info.png)I think it's important to remember the pros and cons of each mode, this image displays it nicely.
+
+1.8 Demonstrate the ability to manage the cache
+-----------------------------------------------
+
+![Magento Question](./images/icon-question.png)**Describe cache types and the tools used to manage caches.**
+
+
+
+| Cache type "friendly" name | Cache type code name | Description |
+| --- | --- | --- |
+| Configuration | `configuration` | Magento collects configuration from all modules, merges it, and saves the merged result to the cache. This cache also contains store-specific settings stored in the file system and database. Clean or flush this cache type after modifying configuration files. |
+| Layout | `layout` | Compiled page layouts (that is, the layout components from all components).Clean or flush this cache type after modifying layout files. |
+| Block HTML output | `block_html` | HTML page fragments per block. Clean or flush this cache type after modifying the view layer.
+| Collections data | `collections` | Results of database queries. If necessary, Magento cleans up this cache automatically, but third-party developers can put any data in any segment of the cache. Clean or flush this cache type if your custom module uses logic that results in cache entries that Magento cannot clean. |
+| DDL | `db_ddl` | Database schema. If necessary, Magento cleans up this cache automatically, but third-party developers can put any data in any segment of the cache. Clean or flush this cache type after you make custom changes to the database schema. (In other words, updates that Magento does not make itself.) One way to update the database schema automatically is using the [`bin/magento setup:db-schema:upgrade`](https://devdocs.magento.com/guides/v2.2/install-gde/install/cli/install-cli-subcommands-db.html&sa=D&ust=1609223264497000&usg=AOvVaw11ISXilTr222oUPOaex6ti) command. |
+| Entity attribute value (EAV) | `eav` | Metadata related to EAV attributes (for example, store labels, links to related PHP code, attribute rendering, search settings, and so on). You should not typically need to clean or flush this cache type. |
+| Page cache | `full_page` | Generated HTML pages. If necessary, Magento cleans up this cache automatically, but third-party developers can put any data in any segment of the cache. Clean or flush this cache type after modifying code level that affects HTML output. It's recommended to keep this cache enabled because caching HTML improves performance significantly. |
+| Reflection | `reflection` | Removes a dependency between the Webapi module and the Customer module. |
+| Translations | `translate` |  Merged translations from all modules. |
+| Integration configuration | `config_integration` |  Compiled integrations. Clean or flush this cache after changing or adding integrations. |
+| Integration API configuration | `config_integration_api` | Compiled integration APIs. |
+| Web services configuration | `config_webservice` | Web API structure. |
+
+
+
+ ![Magento Exam Notes - More information](./images/icon-info.png)I wouldn't think you'd be expected to remember this, these cache types are available in the admin but it might pay to understand roughly what each cache type does when presented with the "friendly" name. Just try to remember: Store module configuration / Layout declaration / Block template HTML output / Translations / Full Page Cache (FPC) / Database Queries.
+
+![Magento Question](./images/icon-question.png)**How do you add dynamic content to pages served from the full page cache?**
+
+*   Mark any block cacheable="false" in layout.xml - renders whole page uncacheable. Example =
+            checkout.
+*   Disable caching in controller using headers:
+
+```php
+$page->setHeader(
+    'Cache-Control',
+    'no-store, no-cache, must-revalidate, max-age=0',
+    true
+);
+```
+
+*   ![Magento Exam Note Warning](images/icon-warning.png)NOTE: deprecated Marking block property isScopePrivate
+            - will be loaded via AJAX
+*   ESI when Varnish enabled, set TTL. For example: Megamenu
+            blocks from common extensions.
+*   Configure page variations - extend http context, more
+            cached versions of same page - store view, customer group, language, currency, is logged
+            in Magento\Framework\App\Http\Context::getVaryString - So when you are not logged in,
+            all guests receive a cached version of the page. When you add a product to cart the
+            query string changes which renders another variation.
+*   Magento 2 [JSComponents](#h.kg229a1fn1nm) for FPC
+            hole-punching.
+*   Magento 2 [Dynamic Blocks](#h.db4onextldi8).
+
+
+![Magento Question](./images/icon-question.png)**Describe how to operate with cache clearing. How would you clean the cache?**
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)Via CLI
+
+
+``` bash
+bin/magento setup:upgrade
+bin/magento setup:db-schema:upgrade
+bin/magento cache:disable
+bin/magento cache:clean
+bin/magento cache:clean full_page
+bin/magento cache:flush
+bin/magento cache:flush full_page
+bin/magento index:reindex
+```
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)Via Admin
+
+
+
+> **Admin > System > Tools > Cache Management**
+
+
+![Magento Question](./images/icon-question.png)**In which case would you refresh (clean) cache vs flush cache storage?**
+
+> When you clean cache, it deletes all items from enabled Magento cache types only. Disabled cache types are not cleaned.
+> When you flush cache, you remove all cache records in storage. It might affect other processes applications that are using the same storage.
+> Re-indexing also clears cache.
+> Performing a `bin/magento setup:upgrade` also clears cache.
+
+
+![Magento Exam Notes - More information](./images/icon-info.png)Important to know the difference between cache clean and cache flush.
+
+![Magento Question](./images/icon-question.png)**Describe how to clear the cache programmatically.**
+
+
+
+Remove cached data by identifier:
+```php
+Magento\Framework\App\CacheInterface::remove(string $identifier);
+```
+
+Clean cached data by specific tag:
+```php
+Magento\Framework\App\CacheInterface::clean(array $tags = []);
+```
+
+![Magento Exam Notes - More information](./images/icon-info.png) Rather than remembering this class name. Remember 2 things:
+
+1.  Cache is part of Magento_Framework module so it's very core.
+2.  Magento likes you to inject interface dependencies thanks to it's automatic type hint allowing the system to search for a <preference> class.
+
+Thus "Magento" "Framework" "Cache" "Interface".
+
+![Magento Question](./images/icon-question.png)**What mechanisms are available for clearing all or part of the cache?**
+
+
+Admin
+> **Admin > System > Tools > Cache Management**
+
+
+CLI
+```bash
+bin/magento cache:clean
+bin/magento cache:clean full_page
+bin/magento cache:flush
+bin/magento cache:flush full_page
+```
+
+Events
+
+> Dispatch a "clean_cache_by_tags" event with
+> parameters of the object you want to clear from the cache. Example:
+> Magento\Framework\Model\AbstractModel (afterSave, afterDelete methods)
+
+
+
+```php
+<?php
+
+......
+
+public function afterSave()
+{
+    $this->cleanModelCache();
+    $this->_eventManager->dispatch('model_save_after', ['object' => $this]);
+    $this->_eventManager->dispatch('clean_cache_by_tags', ['object' => $this]);
+    $this->_eventManager->dispatch($this->_eventPrefix . '_save_after', $this->_getEventData());
+    $this->updateStoredData();
+    return $this;
+}
+
+public function cleanModelCache()
+{
+    $tags = $this->getCacheTags();
+    if ($tags !== false) {
+        /** @var Magento\Framework\App\CacheInterface */
+        $this->_cacheManager->clean($tags);
+    }
+    return $this;
+}
+
+```
+
+![Magento Question](./images/icon-question.png)**Describe Cache Types. How would you create your own Cache Type?**
+
+> Caching is the storage of data for future retrieval / usage. It's designed to speed up future requests. Or is it a way to mask poorly optimised code...
+
+
+Magento uses caching to quickly display Categories, Products, and CMS
+                            pages. Full-page caching in particular improves response time and reduces the load on the
+                            server. Without caching, each page might need to run blocks of code and retrieve information
+                            from the database. However, with full-page caching enabled, a fully-generated page can be
+                            read directly from the cache.
+
+Magento recommends that Varnish Cache be used as the
+                            caching applications and only in a production environment.
+
+Cached content can be used
+                            to process the requests from similar types of visits. As a result, pages shown to a casual
+                            visitor might differ from those shown to a customer. For the purposes of caching, each visit
+                            is one of three types:
+
+
+
+*   Non-sessioned - During a non-sessioned visit, a shopper views pages, but does not interact with the store. The
+            system caches the content of each page viewed and serves them to other non-sessioned
+            shoppers.
+*   Sessioned - During a sessioned
+            visit, shoppers who interact with the store -- through activities such as comparing
+            products or adding products to the shopping cart -- are assigned a session ID. Cached
+            pages that are generated during the session are used only by that shopper during the
+            session.
+*   Customer - Customer sessions are
+            created for those who have registered for an account with your store and shop while
+            logged in to their accounts. During the session, customers can be presented with special
+            offers, promotions, and prices that are based on their assigned customer group.
+
+
+Creating your own cache type
+
+#### cache.xml
+
+> A cache type enables you to specify what is cached and enables
+> merchants to clear that cache type using the Cache Management page in the Magento Admin. See
+> above for all available cache types. The following is an example for demonstration purposes only
+
+
+`<module_dir>/etc/cache.xml`
+```xml
+<?xml version="1.0"?>
+
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Cache/etc/cache.xsd">
+    <type name="example_cache_type" translate="label,description" instance="MyVendor\MyModule\Model\Cache\Type\Example">
+        <label>Example Cache Type</label>
+        <description>Example of how to create a cache type using declarative schema</description>
+    </type>
+</config>
+```
+
+Cache Type example:
+
+`MyVendor\MyModule\Model\Cache\Type\Example`
+```php
+<?php
+
+namespace MyVendor\MyModule\Model\Cache\Type;
+
+use Zend_Cache;
+use Magento\Framework\App\ObjectManager;
+use Magento\Framework\App\Cache\Type\FrontendPool;
+use Magento\Framework\App\Cache\TypeListInterface;
+use Magento\Framework\Cache\Frontend\Decorator\TagScope;
+use Magento\PageCache\Model\Cache\Type as FullPageCache;
+
+/** Admin > System > Cache Management > Cache type: "Example Cache Type" */
+class Example extends TagScope
+{
+    /** @var string Cache type code unique among all cache types */
+    const TYPE_IDENTIFIER = 'example';
+
+    /** @var string The tag name that limits the cache cleaning scope within a particular tag */
+    const CACHE_TAG = 'example';
+
+    /** @var FullPageCache */
+    private $fullPageCache;
+
+    /** @var TypeListInterface */
+    protected $typeList;
+
+    /**
+     * @param FrontendPool $cacheFrontendPool
+     * @param TypeListInterface $typeList
+     */
+    public function _construct(
+        FrontendPool $cacheFrontendPool,
+        TypeListInterface $typeList
+
+    ) {
+        parent::_construct(
+            $cacheFrontendPool->get(self::TYPE_IDENTIFIER),
+            self::CACHE_TAG
+        );
+        $this->typeList = $typeList;
+    }
+
+    /**
+     * WARNING: Use this method lightly as the whole site can be affected here without hole-punching.
+     * @return FullPageCache
+     */
+
+    private function getFullPageCache(): FullPageCache
+    {
+        if (!$this->fullPageCache) {
+            $this->fullPageCache = ObjectManager::getInstance()->get(FullPageCache::class);
+        }
+        return $this->fullPageCache;
+    }
+
+    public function cleanByTags(array $postRelatedProductIds): bool
+    {
+        $tags = [];
+        foreach ($postRelatedProductIds as $postRelatedProductId) {
+            $tags[] = static::CACHE_TAG . '_' . $postRelatedProductId;
+        }
+        return $this->clean(Zend_Cache::CLEANING_MODE_MATCHING_TAG, $tags);
+    }
+
+    public function cleanTag(): bool
+    {
+        return $this->clean(Zend_Cache::CLEANING_MODE_MATCHING_TAG, [static::CACHE_TAG]);
+    }
+}
+
+```
+
+
+> Finally, this can be outputted somewhere in any block class that
+> implements Magento\Framework\DataObject\IdentityInterface this way
+> you will see such tags (ex, ex_1) in the request headers of any page that renders this block
+> such as:
+
+```bash
+curl -I -k https://example.localhost/my-example-page/
+
+HTTP/2 200
+x-magento-tags: store,cms_b,cms_b_footer-top-content,cms_b_footer-middle-logo,cms_b_footer-middle-newsletter,cms_b_footer-middle-link,cms_b_footer-payment-logo,cms_b_footer-bottom-copyright,cms_b_footer-bottom-braintrees,cms_b_header-top-wrapper,aw_blog_category_sidebar,cms_b_0,ex,ex_1
+```
+
+> When you clean caches by tag (i.e. `MyVendor\MyModule\Model\Cache\Type\Example::cleanTag`) then any page matching these tag types will be purged.
+
+
+
+
+> Block class example implementing Magento\Framework\DataObject\IdentityInterface
+
+```php
+<?php
+
+namespace MyVendor\MyModule\Block;
+
+use Magento\Framework\View\Element\Template;
+use Magento\Framework\DataObject\IdentityInterface;
+use MyVendor\MyModule\Model\Cache\Type\Example;
+
+class Example extends Template implements IdentityInterface
+{
+    public function getIdentities()
+    {
+        $identities = [Example::CACHE_TAG];
+        foreach ($this->getSomeIds() as $id) {
+            $identities[] = Example::CACHE_TAG . '_' . $id;
+        }
+        return $identities;
+    }
+}
+
+```
+
+![Magento Question](./images/icon-question.png)**What is the difference between full_page Cache (FPC) and the other cache types?**
+
+
+
+There are 3 common terms:
+1.  Cold Cache - When there's nothing stored for
+            retrieval.
+2.  Warm Cache - When content is available for
+            retrieval.
+3.  Full Page Cache (FPC) - Caching of the entire
+            page.
+
+
+
+
+
+![Magento Question](./images/icon-question.png)**How would you hole-punch FPC?**
+
+### ![Magento Answer Section - Chevron](./images/icon-chevron.png)JavaScript Component
+
+
+> A JSComponent with AJAX request would be one effective way to by-pass information from being cached and keep output dynamic.
+> A JSComponent is a RequireJS module.
+> Magento will load these based on JSON given in custom script tags or data-* attributes. The crucial difference is that this module has to return a function. This function will be called with two arguments: the configuration object passed via the JSON, and the element (singular, non-jQuery object) that the component is called on. It is called once per matched element.
+
+
+
+First we define RequireJs configuration:
+
+`requirejs-config.js`
+```js
+var config = {
+    map: {
+        '*': {
+            exampleJsComponent: 'MyVendor_MyModule/js/model/example'
+        }
+    }
+};
+```
+
+>Next we declare our JSComponent using XML Layout declarative schema.
+>For the purpose of this example, the product view page has been chosen as this would be an
+> example of a cached page (unlike checkout).
+
+`catalog_product_view.xml`
+```xml
+<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" layout="1column" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
+    <body>
+        <referenceContainer name="product.info.main">
+            <block class="Magento\Catalog\Block\Product\View" name="example" template="MyVendor_MyModule::product/view/example.phtml">
+                <arguments>
+                    <argument name="jsLayout" xsi:type="array">
+                        <item name="types" xsi:type="array"/>
+                        <item name="components" xsi:type="array">
+                            <item name="exampleJsComponent" xsi:type="array">
+                                <item name="component" xsi:type="string">exampleJsComponent</item>
+                                <item name="config" xsi:type="array">
+                                    <item name="template" xsi:type="string">'MyVendor_MyModule/view/example</item>
+                                </item>
+                            </item>
+                        </item>
+                    </argument>
+                </arguments>
+            </block>
+        </referenceContainer>
+    </body>
+</page>
+```
+
+
+> Next we specify custom script tags with JSON of which to load this RequireJs Module.
+
+
+
+
+`MyVendor_MyModule::product/view/example.phtml`
+```html
+<?php
+
+/**
+ * @var \Magento\Catalog\Block\Product\View $block
+ * @var \Magento\Catalog\Model\Product $_product
+ */
+$_product = $block->getProduct();
+?>
+
+<script type="text/javascript">
+    window.example = (window.example) ? window.example : {};
+    window.example.uri = "https://jsonplaceholder.typicode.com/todos/1";
+    window.example.title = "<?= $_product->getName(); ?> ?>";
+</script>
+
+<div id="example" data-bind="scope:'exampleJsComponent'">
+    <!-- ko template: getTemplate() --><!-- /ko -->
+    <script type="text/x-magento-init">
+    {
+        "#example": {
+            "Magento_Ui/js/core/app":  <?= /* @escapeNotVerified */ $block->getJsLayout(); ?>
+        }
+    }
+    </script>
+</div>
+```
+
+> Now for the meaty part, the JSComponent itself with the AJAX Request.
+
+
+`MyVendor_MyModule/js/model/example`
+
+```js
+define(
+    [
+        'ko',
+        'jquery',
+        'uiComponent',
+        'mage/cookies'
+    ],
+    function (
+        ko,
+        $,
+        Component
+    ) {
+        'use strict';
+
+        const PRODUCT_DATA = window.exampleData;
+
+        return Component.extend({
+
+            /**
+             * @var {Object}
+             */
+            description: ko.observable(PRODUCT_DATA.description),
+
+            /**
+             * @var {Object}
+             */
+            title: ko.observable(PRODUCT_DATA.title),
+
+            /**
+             * @var {Object}
+             */
+
+            defaults: {
+                template: 'MyVendor_Module/view/example'
+            },
+
+            /**
+             * Constructor
+             */
+
+            initialize: function () {
+
+                this._super();
+                $(document).ready(() => this.ready());
+
+                return this;
+            },
+
+            /**
+             * DOM Loaded
+             */
+            ready: function () {
+
+                this.ajaxRequest(
+                    {},
+                    PRODUCT_DATA.uri
+                ).then(
+                    (response) => {
+                        this.description(response);
+                    }
+                ).catch(
+                    (err) => {
+                        console.error(err);
+                    }
+                );
+            },
+
+            /**
+            * @param {Object|JSON} data
+            * @param {String} uri
+            * @return {Promise}
+            */
+            ajaxRequest: function (data, uri) {
+
+                data['form_key'] = $.mage.cookies.get('form_key');
+                const contentType = (data instanceof Object) ? "application/x-www-form-urlencoded; charset=UTF-8" : "application/json; charset=UTF-8";
+                return new Promise((resolve, reject) => {
+
+                    $.ajax({
+                        url: uri,
+                        type: 'POST',
+                        dataType: "json",
+                        contentType: contentType,
+                        showLoader: true,
+                        data: data,
+                        timeout: 30000,
+                        success: (data, textStatus, jQxhr) => {
+                            resolve(data);
+                        },
+                        error: (jqXhr) => {
+                            reject(jqXhr);
+                        }
+                    });
+                });
+            }
+        });
+    }
+);
+```
+
+> Finally, the template file which was defined in both the XML Layout and JSComponent
+
+`MyVendor_Module/view/example`
+```html
+<strong data-bind="text: title"></strong>
+<p data-bind="text: description"></p>
+```
+
+### ![Magento Answer Section - Chevron](./images/icon-chevron.png)Magento Dynamic Blocks (Magento enterprise/commerce only).
+
+
+
+> Dynamic Blocks are rich, interactive content that is driven by logic from [Price Rules](#h.5wkclkkw15ho) and [Customer Segments](https://docs.magento.com/user-guide/marketing/customer-segments.html&sa=D&ust=1609223264553000&usg=AOvVaw1wyY9x_gmS7G01s_Yx-eAH).
+
+
+They can be created via the Admin:
+> **Admin > Content > Elements > Dynamic Blocks**
+
+
+![Magento Exam Notes - More information](./images/icon-info.png)[More information on Dynamic Blocks here](https://docs.magento.com/user-guide/cms/dynamic-blocks.html&sa=D&ust=1609223264554000&usg=AOvVaw30Kq-Ec3OfDFsYQ7ld07Tg)
\ No newline at end of file
diff --git a/10. Customer Management/10.1 Demonstrate ability to customize My Account.md b/10. Customer Management/10.1 Demonstrate ability to customize My Account.md
deleted file mode 100644
index 1edfc15..0000000
--- a/10. Customer Management/10.1 Demonstrate ability to customize My Account.md	
+++ /dev/null
@@ -1,34 +0,0 @@
-## 10.1 Demonstrate ability to customize My Account
-
-Describe how to customize the “My Account” section. 
-
-*How do you add a menu item?*
-- Create A theme or use an existing one
-- Create a folder in the theme Magento_Customer
-- Create a folder inside the theme Magento_Customer called layout 
-- Create a file inside the theme/Magento_Customer/layout/customer_account.xml
-- Add similar xml
-```xml
-<?xml version="1.0"?>
-<!--
-/**
- * Copyright © Magento, Inc. All rights reserved.
- * See COPYING.txt for license details.
- */
--->
-<page  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
-    <body>
-        <referenceBlock name="customer_account_navigation">
-            <block class="Magento\Customer\Block\Account\SortLinkInterface" name="customer-account-navigation-address-link">
-                <arguments>
-                    <argument name="label" xsi:type="string" translate="true">Russell Special</argument>
-                    <argument name="path" xsi:type="string">special/link</argument>
-                    <argument name="sortOrder" xsi:type="number">165</argument>
-                </arguments>
-            </block>
-        </referenceBlock>
-    </body>
-</page>
-```
-
-*How would you customize the “Order History” page?*
diff --git a/10. Customer Management/10.2 Demonstrate ability to customize customer functionality.md b/10. Customer Management/10.2 Demonstrate ability to customize customer functionality.md
deleted file mode 100644
index 212ca01..0000000
--- a/10. Customer Management/10.2 Demonstrate ability to customize customer functionality.md	
+++ /dev/null
@@ -1,21 +0,0 @@
-## 10.2 Demonstrate ability to customize customer functionality
-
-Describe how to add or modify customer attributes.
-
-Describe how to extend the customer entity. 
-
-*How would you extend the customer entity using the extension attributes mechanism?*
-
-Describe how to customize the customer address. 
-
-*How would you add another field into the customer address?*
-
-Describe customer groups and their role in different business processes. 
-
-*What is the role of customer groups?*
-
-*What functionality do they affect?*
-
-Describe Magento functionality related to VAT. 
-
-*How do you customize VAT functionality?*
diff --git a/10.Magento-Customer-Management.md b/10.Magento-Customer-Management.md
new file mode 100755
index 0000000..a842bfa
--- /dev/null
+++ b/10.Magento-Customer-Management.md
@@ -0,0 +1,433 @@
+10 - Customer Management
+========================
+
+10.1 Demonstrate ability to customize My Account
+------------------------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**Describe how to customize the "My Account" section.**
+
+> Magento_Customer module is responsible for the user account functioning. If you need to modify in some way the user account (for instance, add new elements, delete the existing ones or change the position of blocks), you need to modify the Magento_Customer module components.
+>
+> We can do this via the following ways:
+
+*   [Create A Storefront Theme](https://devdocs.magento.com/guides/v2.4/frontend-dev-guide/themes/theme-create.html&sa=D&ust=1609223266250000&usg=AOvVaw2t16x04YpZnZUGweZfJOP7) then [apply & configure it](https://devdocs.magento.com/guides/v2.4/frontend-dev-guide/themes/theme-apply.html&sa=D&ust=1609223266251000&usg=AOvVaw1QcmFf_qO5ciuHbJGsNtDR). Alternatively you can use an existing one theme (Magento/blank for example) Or even [Create a Module](#h.8r6t4fakpxnh).
+*   Create a folder in the theme `Magento_Customer/layout`, or (if using a custom Module): `<module_dir>/view/frontend/layout`
+*   The following layout files are available for customisation:
+
+    *   `customer_account_confirmation.xml`
+    *   `customer_account_createpassword.xml`
+    *   `customer_account_create.xml`
+    *   `customer_account_edit.xml`
+    *   `customer_account_forgotpassword.xml`
+    *   `customer_account_index.xml`
+    *   `customer_account_login.xml`
+    *   `customer_account_logoutsuccess.xml`
+    *   `customer_account.xml`
+    *   `customer_address_form.xml`
+    *   `customer_address_index.xml`
+    *   `default.xml` (all pages)
+
+![Magento Exam Information](./images/icon-info.png)Main thing to remember here are: `customer_account_*.xml` layout update handles and default.xml Where these layouts go (Theme / Module) is more outta scope for this question.
+
+![Magento Exam Question](./images/icon-question.png)**How do you add a menu item?**
+
+> To add a new menu item, add the following instruction into customer_account.xml file specifically. For example:
+
+```xml
+<referenceBlock name="customer_account_navigation">
+    <block class="Magento\Customer\Block\Account\SortLinkInterface" name="customer-account-navigation-address-link">
+        <arguments>
+            <argument name="label" xsi:type="string" translate="true">My awesome menu item</argument>
+            <argument name="path" xsi:type="string">path/i/need</argument>
+            <argument name="sortOrder" xsi:type="number">100</argument>
+        </arguments>
+    </block>
+</referenceBlock>
+```
+
+> We add a new block of the interface instance `Magento\Customer\Block\Account\SortLinkInterface` (or a concrete class that implements it) class and pass the menu arguments:
+
+*   `label` (name)
+*   `page` (link)
+*   `sortOrder` (position)
+
+> As a result, a new menu item will appear in the user menu:
+
+![](./images/Magento-2-Certified-Professional-Developer-Guide-Screenshot-79.jpg)
+
+> To delete the existing menu item, apply the following instruction in your customer_account.xml:
+
+```xml
+<referenceBlock name="name-of-the-link-to-remove" remove="true" />
+```
+
+> Finally, when we need to change the block order, we can modify the sortOrder argument value. For example, let us make the Wishlist section the first menu item:
+
+```xml
+<referenceBlock name="customer-account-navigation-wish-list-link">
+    <arguments>
+        <argument name="sortOrder" xsi:type="number">500</argument>
+    </arguments>
+</referenceBlock>
+```
+![Magento Exam Information](./images/icon-info.png)Following the rule above here of just remembering the layout name: customer_account_*.xml you apply common sense and if presented with a customer_account.xml option in the exam - this looks correct to edit the Customer Account page.
+
+![Magento Exam Question](./images/icon-question.png)**How would you customize the "Order History" page?**
+
+> To customize My Orders page, modify the layout-file sales_order_history.xml of the Magento_Sales module. For this, create a sales_order_history.xml file and place it in our theme at the following path: Magento_Sales/layout/. Then, apply any instructions, provided in Magento 2 for layout customization. For example, let us add a text block before the orders list:
+
+```xml
+<referenceContainer name="sales.order.history.info">
+    <block class="Magento\Framework\View\Element\Text" name="my_text">
+        <arguments>
+            <argument name="text" xsi:type="string">Hey! I have been added to demonstrate the ability to adding the new blocks!</argument>
+        </arguments>
+    </block>
+</referenceContainer>
+```
+
+> As a result, on the My Orders page in the user account we will see the following text:
+
+![](./images/Magento-2-Certified-Professional-Developer-Guide-Screenshot-80.jpg)
+
+> To modify the order table contents (for example, add a new column), we need to override the `vendor/magento/module-sales/view/frontend/templates/order/history.phtml` template.
+
+![Magento Exam Information](./images/icon-info.png)This one is a tad mis-leading as it's actually within the `Magento_Sales` sales module rather than `Magento_Customer` - as long as you remember this, then `sales_order_history.xml` / `order/history.phtml` layout / templates would appear to make sense.
+
+10.2 Demonstrate ability to customize customer functionality
+------------------------------------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**Describe the customer entity.**
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Customers
+
+> A Customer is its own Magento Entity within the Magento_Customer module.
+> Like all Modules, Magento_Customer uses the [Service Contracts](https://devdocs.magento.com/guides/v2.3/extension-dev-guide/service-contracts/service-contracts.html&sa=D&ust=1609223266259000&usg=AOvVaw2KGjEGSyVnYNDGQI08Xl8Z) design pattern to manage (C.R.U.D actions) on the Customers Entity. Here are a few (notable) Repositories:
+
+> Main Customer CRUD interface
+
+```php
+Magento\Customer\Api\CustomerRepositoryInterface::save(
+    \Magento\Customer\Api\Data\CustomerInterface $customer,
+    $passwordHash = null
+);
+```
+
+> Interface for managing customers accounts
+
+```php
+Magento\Customer\Api\AccountManagementInterface::createAccount(
+    \Magento\Customer\Api\Data\CustomerInterface $customer,
+    $password = null,
+    $redirectUrl = ''
+);
+```
+
+> Customer Address CRUD interface
+```php
+Magento\Customer\Api\AddressRepositoryInterface::save(
+    \Magento\Customer\Api\Data\AddressInterface $address
+);
+```
+
+> Main Customer Address Data Interface
+
+```php
+Magento\Customer\Api\Data\AddressInterface::getCountryId();
+```
+
+> Interface For Managing Customer Groups.
+
+```php
+Magento\Customer\Api\GroupRepositoryInterface::save(
+    \Magento\Customer\Api\Data\GroupInterface $group
+);
+```
+
+> Customer Group Data Interface
+
+```php
+Magento\Customer\Api\Data\GroupInterface::getTaxClassId();
+```
+
+> Interface For Managing Customer Groups
+
+```php
+Magento\Customer\Api\GroupManagementInterface::getDefaultGroup(
+    $storeId = null
+);
+```
+
+> Interface For System Configuration Operations For Customer Groups
+
+```php
+Magento\Customer\Api\CustomerGroupConfigInterface::setDefaultCustomerGroup(
+    int $id
+);
+```
+
+> Interface For Getting Attributes Metadata (Note that this interface should not be used directly, use its children).
+
+```php
+Magento\Customer\Api\MetadataInterface::getAttributes();
+```
+
+> Customer Attribute Metadata Interface
+
+```php
+Magento\Customer\Api\Data\AttributeMetadataInterface::getIsUsedInGrid();
+```
+
+![Magento Exam Information](./images/icon-info.png)Main thing to remember here is that the Magento_Customer module is responsible for the Customer Entity. Within this module are repositories that conform to the [Service Contract](https://devdocs.magento.com/guides/v2.3/extension-dev-guide/service-contracts/service-contracts.html&sa=D&ust=1609223266265000&usg=AOvVaw2QEerRAv1hfxHcgYE6cZC6) design pattern which create injectable repositories for the following entities: Customer, Customer Address, Customer Groups.
+
+| Database Table: `customer_entity` | Notable Columns | Description |
+| --- | --- | --- |
+| Core Customer Properties | `entity_id` - int(10), `website_id` - smallint(5), `created_at` - timestamp, `updated_at` - timestamp, email - varchar(255), `group_id` - smallint(5), `increment_id` - varchar(50), `store_id` - smallint(5), `is_active` - decimal(12,4), `disable_auto_group_change` - smallint(5), `created_in` - varchar(255) | `entity_id`: used all over the code and is the global identifier. `email`: The customer's email address. `is_active`: Used for status. `increment_id`: Changing the initial customer increment id (if you want it different from default). `group_id`: The ID of the customer group where the customer is assigned. `disable_auto_group_change` Determines if customer groups can be dynamically assigned during [](https://docs.magento.com/user-guide/tax/vat-validation.html&sa=D&ust=1609223266269000&usg=AOvVaw1LhR3NMIt-SJ1xCmzH32MB) [VAT ID validation](https://docs.magento.com/user-guide/tax/vat-validation.html&sa=D&ust=1609223266269000&usg=AOvVaw1LhR3NMIt-SJ1xCmzH32MB). `created_in`: The store view where the account was created. |
+| Customer Properties | `prefix` - varchar(40), `firstname` - varchar(255), `middlename` - varchar(255), `lastname` - varchar(255), `suffix` - varchar(40), `dob` - `date`, `taxvat` - varchar(50), `confirmation` - varchar(64), `default_billing` - int(10), `default_shipping` - int(10), `failures_num` - smallint(6), `first_failure` - timestamp, `lock_expires` - timestamp | `prefix`: Any prefix that is used with the customer name.(Mr., Ms., Mrs., Dr., etc.). `firstname`: The first name of the customer. `middlename`: The middle name or middle initial of the customer. `lastname`: The last name of the customer. `suffix`: Any suffix that is used with the customer name. (Jr., Sr., Esquire, etc.). `dob`: The customer's date of birth. `taxvat`: The [Value Added Tax (VAT)](https://docs.magento.com/user-guide/tax/vat.html&sa=D&ust=1609223266275000&usg=`AOvVaw2IrzV3sr_zb0qGTszTbjrV`) ID that is assigned to the customer. The default label of this attribute is "VAT Number". The VAT number field is always present in all shipping and billing customer addresses when viewed from the Admin, but is not a required field. `gender`: The customer gender. `default_billing`: The user selected default Billing Address ID `default_shipping`: The user selected default Shipping Address ID |
+
+![Magento Exam Information](./images/icon-info.png)[More information on Customers here](https://docs.magento.com/user-guide/stores/attributes-customer.html&sa=D&ust=1609223266278000&usg=AOvVaw2oivunhnbBQMDCY90HW5Pb)
+
+![Magento Exam Information](./images/icon-info.png)(Magento commerce/enterprise only) It is worth mentioning that in Magento Commerce you are able to add/edit Customer Attributes via Admin > Stores > Attributes > Customer
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Customer Address Attributes
+
+| Database Table: `customer_address_entity` | Notable Columns | Description |
+| --- | --- | --- |
+| Core Customer Address Properties | `entity_id` - int(10), `parent_id` - int(10), `created_at` - timestamp, `updated_at` - timestamp, `is_active` - smallint(5) | `entity_id`: used all over the code and is the global identifier. `is_active`: Used for status. If value = 0, then it won't appear in the checkout for the customer. `increment_id`: Changing the initial customer increment id (if you want it different from default). `parent_id`: The ID of the customer.
+| Customer Address Properties | `city` - varchar(255), `company` - varchar(255), `country_id` - varchar(255), `fax` - varchar(255), `firstname` - varchar(255), `lastname` - varchar(255), `middlename` - varchar(255), `postcode` - varchar(255), `prefix` - varchar(40), `region` - varchar(255), `region_id` - int(10), `street` - text, `suffix` - varchar(40), `telephone` - varchar(255), `vat_id` - varchar(255), `vat_is_valid` - int(10), `vat_request_date` - varchar(255), `vat_request_id` - varchar(255), `vat_request_success` - int(10) | `country_id`: Two-letter country code in ISO_3166-2 format. `region`: e.g. Queensland (part of Magento\Customer\Api\Data\RegionInterface class). `region_id`: The middle name or middle initial of the customer. `postcode`: Zipcode. `vat_id`: The [Value Added Tax (VAT)](https://docs.magento.com/user-guide/tax/vat.html&sa=D&ust=1609223266285000&usg=AOvVaw0coHcdWFT_M-1U70VZ94Is) ID that is assigned to the customer. The default label of this attribute is "VAT Number". The VAT number field is always present in all shipping and billing customer addresses when viewed from the Admin, but is not a required field. |
+| Unused columns | `increment_id` - varchar(50) | |
+
+![Magento Exam Information](./images/icon-info.png)[More information on Customer Address here](https://docs.magento.com/user-guide/stores/attributes-customer-address.html&sa=D&ust=1609223266286000&usg=AOvVaw0yclXlWq1FZq0qgRmknLgp) & [here](https://devdocs.magento.com/compliance/privacy/pi-data-reference-m2.html&sa=D&ust=1609223266286000&usg=AOvVaw3twE6Mmh_Rcjp8-c-Vy6Ho).
+
+![Magento Exam Information](./images/icon-info.png)It's worth noting that much information is duplicated here (customer information) as well as address information being duplicated in the sales_order_address table. This follows the data de-normalisation approach and is used because each serves different purposes. For example: if a customer removes and address then it should not then be removed from any previous orders.
+
+![Magento Exam Information](./images/icon-info.png)(Magento commerce/enterprise only) It is also worth mentioning that in Magento Commerce you are able to add/edit Customer Address Attributes via Admin > Stores > Attributes > Customer Address
+
+![Magento Exam Question](./images/icon-question.png)**Describe how to add or modify customer attributes.**
+
+> To create a new customer attribute, we can use Data Setup script in the form of a Create a Customer [Data Patch](#h.fb7s5a4nvxv9):
+
+```php
+<?php
+
+namespace MyVendor\MyModule\Setup\Patch\Data;
+
+use Magento\Customer\Model\Customer;
+use Magento\Customer\Setup\CustomerSetupFactory;
+use Magento\Eav\Model\Entity\Attribute\SetFactory;
+use Magento\Eav\Api\AttributeRepositoryInterface;
+use Magento\Framework\Exception\NoSuchEntityException;
+use Magento\Framework\Setup\Patch\DataPatchInterface;
+use Magento\Framework\Setup\ModuleDataSetupInterface;
+use Magento\Framework\Setup\Patch\PatchRevertableInterface;
+
+class DummyDataPatch implements DataPatchInterface, PatchRevertableInterface
+{
+    /** @var CustomerSetupFactory */
+    private $customerSetupFactory;
+
+    /** @var SetFactory */
+    private $attributeSetFactory;
+
+    /** @var ModuleDataSetupInterface */
+    private $moduleDataSetup;
+
+    /** @var AttributeRepositoryInterface */
+    private $attributeRepository;
+
+    public function __construct(
+        ModuleDataSetupInterface $moduleDataSetup,
+        CustomerSetupFactory $customerSetupFactory,
+        AttributeRepositoryInterface $attributeRepository,
+        SetFactory $attributeSetFactory
+    ) {
+        $this->moduleDataSetup = $moduleDataSetup;
+        $this->customerSetupFactory = $customerSetupFactory;
+        $this->attributeSetFactory = $attributeSetFactory;
+        $this->attributeRepository = $attributeRepository;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function apply()
+    {
+        $setup = $this->moduleDataSetup->getConnection()->startSetup();
+        $customerSetup = $this->customerSetupFactory->create(['setup' => $setup]);
+        try {
+            $attribute = $this->attributeRepository->get(Customer::ENTITY, 'my_new_attribute');
+        } catch (NoSuchEntityException $e) {
+            // Good, it doesn't exist. Create it.
+            $customerSetup->addAttribute(Customer::ENTITY, 'my_new_attribute', [
+                'type' => 'varchar',
+                'label' => 'My new attribute',
+                'input' => 'text',
+                'required' => false,
+                'visible' => true,
+                'user_defined' => true,
+                'system' => false,
+                'used_in_forms' => [
+                    'adminhtml_customer',
+                    'adminhtml_checkout',
+                    'checkout_register',
+                    'customer_account_create',
+                    'customer_account_edit',
+                ]
+            ]);
+        }
+
+        $this->moduleDataSetup->getConnection()->endSetup();
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public static function getDependencies()
+    {
+        return [];
+    }
+
+    public function revert()
+    {
+        // Revert operations here
+        $customerSetup = $this->customerSetupFactory->create(['setup' => $setup]);
+        try {
+            $attribute = $this->attributeRepository->get(Customer::ENTITY, 'my_new_attribute');
+            if ($attribute) {
+                $customerSetup->removeAttribute(Customer::ENTITY, $attribute->getAttributeCode());
+            }
+        } catch (NoSuchEntityException $e) {
+            // Good, it doesn't exist. No need to revert.
+        }
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getAliases()
+    {
+        return [];
+    }
+}
+```
+
+> Customer attributes can be displayed in different forms, which are set in the used_in_forms array parameter.
+>
+> The list of forms can be found in customer_form_attribute table list available are:
+
+*   `adminhtml_checkout`
+*   `adminhtml_customer`
+*   `adminhtml_customer_address`
+*   `checkout_register`
+*   `customer_account_create`
+*   `customer_account_edit`
+*   `customer_address_edit`
+*   `customer_register_address`
+
+> To modify the attribute, use `Magento\Customer\Setup\CustomerSetupFactory` or `Magento\Eav\Api\AttributeRepositoryInterface` if you want to get it by Attribute Code:
+
+`Magento\Customer\Setup\CustomerSetupFactory`
+```php
+$customerSetup = $this->customerSetupFactory->create(['setup' => $setup]);
+$customerSetup->updateAttribute(\Magento\Customer\Model\Customer::ENTITY, 'new_attribute', 'visible', false);
+```
+
+`Magento\Eav\Api\AttributeRepositoryInterface`
+```php
+$attribute = $this->attributeRepository->get(Customer::ENTITY, 'my_new_attribute');
+$attribute->setData('used_in_forms', ['adminhtml_customer']);
+$this->attributeRepository->save($attribute);
+```
+
+![Magento Exam Question](./images/icon-question.png)**How would you extend the customer entity using the extension attributes mechanism?**
+
+> Module developers can not modify API Data interfaces, described in core Magento 2, but the majority of the modules have the [Extension Attributes](#h.aqe3c923mrz4) mechanism. [Extension Attributes](#h.aqe3c923mrz4) are set and stored separately from the data object of the initial class, so everything, connected with data storage and extraction, must be realized by the developer himself.
+
+![Magento Exam Information](./images/icon-info.png)Please refer to the [Extension Attributes](#h.aqe3c923mrz4) section for more information.
+
+![Magento Exam Question](./images/icon-question.png)**Describe how to customize the customer address. How would you add another field into the customer address?**
+
+> Magento has a standard set of attributes for the Customer Address entity, stored in customer_address_entity table ([see above](#h.l7dt83731myl) for the main columns of this table). Other attributes of the address need to be added as EAV attributes. They will work via Custom Attributes.
+>
+> To add new fields into the Customer Address entity, please do the following:
+
+1.  Create an EAV attribute using `Magento\Customer\Setup\CustomerSetupFactory`. [Please see the Data Patch in the previous question above](#h.l7dt83731myl) for more information on how to achieve this.
+
+![Magento Exam Question](./images/icon-question.png)**Describe customer groups and their role in different business processes. What is the role of customer groups? What functionality do they affect?**
+
+![Magento Section Chevron](./images/icon-chevron.png)Customer Groups
+
+> User/Customer Groups allow you to categorise Users and provide certain functionality based on their groups, these functions include:
+
+*   Modify taxes based on Customer Groups.
+*   Different catalog product pricing based on Customer Groups (tiered prices for example).
+*   Create [Catalog Price Rules](#h.y3a3xjg08db) specific to certain Customer Groups
+*   Create [Cart/Sales Price Rules](#h.9it0avmbiyyv) specific to certain Customer Groups
+*   Create [Cart/Sales Price Rules](#h.9it0avmbiyyv) based on [Customer Segments](https://docs.magento.com/user-guide/marketing/customer-segments.html&sa=D&ust=1609223266306000&usg=AOvVaw14L718FqVeQ1ioscj0DJU_) (Magento Enterprise/Commerce only feature).
+*   Separate their rights/permissions at the storefront side such as disabling guest checkout in Stores > Settings > Configuration > Sales > Checkout > Checkout Options
+*   Filter grid by Customer Groups in the Admin.
+
+> There are the following default user groups:
+
+*   NOT LOGGED IN
+*   General
+*   Wholesale
+*   Retailer
+
+> NOT LOGGED IN is the only user group that you can not delete (same as you can not delete the default registered users group, but, in contrast to NOT LOGGED IN, it is not static, which means it can be modified). NOT LOGGED IN is assigned to all the visitors without a session and determines the type of shopping cart (guest cart). General is the default group for the newly registered users.
+
+![Magento Exam Information](./images/icon-info.png)[Customer Segments](https://docs.magento.com/user-guide/marketing/customer-segments.html&sa=D&ust=1609223266309000&usg=AOvVaw2LmfpaspHl9m-GdIwLJ3OG) allow you to dynamically display content and promotions to specific customers, based on properties such as customer address, order history, shopping cart contents, and so on. You can optimize marketing initiatives based on targeted segments with shopping cart price rules. You can also generate reports and export the list of targeted customers. Because customer segment information is constantly refreshed, customers can become associated and dissociated from a segment as they shop in your store. NOTE: This is not specific to Customer Groups but a useful feature to add here.
+
+![Magento Section Chevron](./images/icon-chevron.png)Company Accounts (Magento B2B feature only)
+
+> On top of **Customer Groups** is also **Company Accounts**
+>
+> A **Company Account** can be set up to reflect the structure of the business. Initially, the company structure includes only the company administrator, but can be expanded to include teams of users. The users can be associated with teams or organized within a hierarchy of divisions and subdivisions within the company.
+>
+>
+> **Company Accounts** can be set up from the storefront OR from the Admin via: Admin > Customers > Companies.
+>
+> By default, the ability to create company accounts from the storefront is enabled. If allowed in the configuration, a visitor to the store can request to open a company account.
+>
+> After the company account is approved, the company administrator can set up the company structure and users with various levels of permission.
+
+![Magento Exam Information](./images/icon-info.png)NOTE: This is not specific to Company Accounts but a useful feature to add here.
+
+![Magento Exam Question](./images/icon-question.png)**Describe Magento functionality related to VAT.**
+
+> Magento is a built-in functionality for working with VAT. VAT depends on the seller's country and buyer's address. When a downloadable product is purchased, VAT depends solely on the delivery destination.
+
+![Magento Exam Question](./images/icon-question.png)**How do you customize VAT functionality?**
+
+> To configure [Value Added Tax](https://docs.magento.com/user-guide/tax/vat.html&sa=D&ust=1609223266314000&usg=AOvVaw2m0N3wThO3aMxl1R9vcFsf) (VAT), you can navigate to the following path:
+>
+> **Admin > Stores > Configuration > General > General > Store Information**
+>
+> VAT Number: this is where you set the seller's VAT number.
+
+![](./images/Magento2-Certification-Exam-Notes-Detailed-Insight-VAT.jpg)
+
+> **Admin > Customers > All Customers > Edit: Customer**
+>
+> Account Information
+>
+> Tax/VAT Number: If applicable, the tax number or value-added tax number that is assigned to the customer
+>
+> Addresses
+>
+> VAT Number: If applicable, the value-added tax number that is associated with a specific billing or shipping address of the customer. For the sale of [](https://docs.magento.com/user-guide/tax/eu-place-of-supply.html&sa=D&ust=1609223266317000&usg=AOvVaw1Wn5M7ae1vk1XUadd6LszX) [digital goods](https://docs.magento.com/user-guide/tax/eu-place-of-supply.html&sa=D&ust=1609223266317000&usg=AOvVaw1Wn5M7ae1vk1XUadd6LszX) within the EU, the amount of the VAT is based on shipping destination.
+>
+> **Admin > Stores > Configuration > Customers > Customer Configuration**
+>
+>
+> Show VAT Number on Storefront: Determines if the customer VAT Number field is included in the Address Book that is available in the customer account.
+>
+> Default Value for Disable Automatic Group Changes Based on VAT ID:
+>
+> VAT ID is an internal identifier for the VAT Number of the customer when used in VAT Validation. During [](https://docs.magento.com/user-guide/tax/vat-validation.html&sa=D&ust=1609223266318000&usg=AOvVaw34MEAbLuB_e7HrNUfU3J56) [VAT Validation](https://docs.magento.com/user-guide/tax/vat-validation.html&sa=D&ust=1609223266318000&usg=AOvVaw34MEAbLuB_e7HrNUfU3J56), Magento confirms that the number matches the [](http://ec.europa.eu/taxation_customs/vies/&sa=D&ust=1609223266319000&usg=AOvVaw2526GcJFWHdE9agT_j1ZrO) [European Commission](http://ec.europa.eu/taxation_customs/vies/&sa=D&ust=1609223266319000&usg=AOvVaw2526GcJFWHdE9agT_j1ZrO) database. Customers can be automatically assigned to one of the four default customer groups based on the validation results.
+>
+> For the correct functioning of VAT in Magento, you should set the Customer Groups and create Tax rules and rates. Tax can be applied separately to Products and Customers with Product Tax Classes and Customer Tax Classes (Admin > Stores > Taxes > Tax Rules); you can also create taxes for certain areas with Tax Zones and Rates (Stores > Taxes > Tax Zones and Rates).
+>
+> To modify Tax, apply `sales_quote_collect_totals_before` event that calculates the order's total cost.
+
+![Magento Exam Information](./images/icon-info.png)In short, VAT is customised via the Admin on both Store/Website and a Customer level configuration.
\ No newline at end of file
diff --git a/11.Magento-Multi-Store-Multi-Website-Scopes.md b/11.Magento-Multi-Store-Multi-Website-Scopes.md
new file mode 100755
index 0000000..30c30d5
--- /dev/null
+++ b/11.Magento-Multi-Store-Multi-Website-Scopes.md
@@ -0,0 +1,202 @@
+11 - Multi-store & Multi-website Scopes
+=======================================
+
+11.1 Describe Multi-store & Multi-website functionality
+-------------------------------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**Outline all the available Magento scopes, what are the scopes available in a standard Magento install?**
+
+> Magento 2 has a 4-level hierarchy: Global, Website, Store (Store Group) & Store View.
+
+![Magento Exam Question](./images/icon-question.png)**What is the difference between Magento 2 website, store, and store view?**
+
+![Magento Section Chevron](./images/icon-chevron.png)Global
+
+> This is the highest level in the Magento pyramid. Here you can set the only 3 options that will be the same for all stores:
+
+1.  Stock - configure the main product settings.
+2.  Price - define the same price for the products in all stores.
+3.  Buyers - Merge all store customer data into one big database for all websites.
+
+![Magento Section Chevron](./images/icon-chevron.png)Global
+
+> Global values are values that are out-of-the-box if the user has not specified. These values are usually defined within a modules `etc/config.xml`.
+>
+> By default, a vanilla Magento install features:
+
+1. System configurations (dependent on their scope in declarative schema `showInDefault`, `showInWebsite`, `showInStore`) available in *Admin > Stores > Configuration*.
+2. No Products
+3. No Customers
+4. 1 Root Category + 1 Default Category without any products
+5. 1 Tax Rule: "Taxable goods", 3 Tax Zones / Rates: US-CA. A Non-taxable goods class is also available.
+6. 1 Website, 1 Store (Store group), 1 Store View.
+
+![Magento Section Chevron](./images/icon-chevron.png)Website
+
+> With one Magento base, you can design various websites, for example, hats.com and pants.com. The following can be configured per Website:
+
+1.  Separate Payment methods.
+2.  Separate Shipping methods.
+3.  A totally separate Product base - products are required to be assigned to websites individually. They can have different prices / currencies / attribute values etc.
+4.  Separate tax classes.
+5.  Separate (base) currencies.
+6.  Separate Customer base - It's up to you whether your customers can log in to all shops with the same credentials.
+7.  System configurations (dependent on their scope in declarative schema `showInDefault`, `showInWebsite`, `showInStore`) available in *Admin > Stores > Configuration*. Mostly all configurations are configurable at this level.
+
+> For each website, you can create multiple stores, but all the information will be gathered in one admin panel.
+
+![Magento Section Chevron](./images/icon-chevron.png)Store (Store Group)
+
+> It's possible to create several stores on one Magento 2 website. The following can be configured per Store:
+
+1.  Different Root Categories which allows for different products to be assigned.
+
+> The following *CANNOT* be configured per Store:
+
+1.  All the stores within one website share the same customer accounts.
+2.  All stores share Shipping Methods.
+3.  All stores share Tax Rates / Zones.
+4.  All stores share Product stock.
+5.  All stores share Product prices.
+6.  All currencies are identical for all the stores.
+7.  System configurations available in *Admin > Stores > Configuration*.
+8.  EAV attributes across entities Customer (including Customer Address), Products, Categories cannot be configured on a Store Group level.
+
+
+![Magento Section Chevron](./images/icon-chevron.png)Store View
+
+> And finally, for every store, you can create several store views. The following can be configured per Store View:
+
+1.  Different languages.
+2.  Different currencies.
+3.  Different design themes
+4.  Certain Product EAV attributes can be different such as name, or tax class (dependent on their `is_global` / `scope` / `is_user_defined` properties).
+5.  Different Category EAV attributes (such as name, or URL key).
+6.  System configurations (dependent on their scope in declarative schema `showInDefault`, `showInWebsite`, `showInStore`) available in *Admin > Stores > Configuration*.
+
+> The following CANNOT be configured per Store View:
+
+1.  All store views within one website share the same customer accounts.
+2.  All store views share Shipping Methods.
+3.  All store views share Tax Rates / Zones.
+4.  All store views share Product stock.
+5.  All store views share Product prices.
+6.  All store views share the same Root Category.
+7.  All currencies are identical for all the store views.
+
+![Magento Exam Notes - More information](./images/icon-info.png)[Here is more information on the subject with infographics!](https://docs.magento.com/user-guide/configuration/scope.html)
+
+![Magento Exam Notes - More information](./images/icon-info.png)[Here is some information regarding Scope System Configuration](https://devdocs.magento.com/guides/v2.4/config-guide/prod/config-reference-systemxml.html)
+
+
+![Magento Exam Question](./images/icon-question.png)**How do you create a new Website, Store & Store View?**
+
+> **Admin > Stores > Settings > All Stores**
+
+![](./images/magento2-all-stores.png)
+
+![Magento Exam Question](./images/icon-question.png)**How do you set up a new Website?**
+
+![Magento Exam Information](./images/icon-info.png)For the purpose of this question we shall assume you are running an Nginx Webserver with PHP-FPM and will specifically focus on the multi-website aspect of the configuration.
+
+```perl
+server {
+        listen 80;
+        server_name mydomain.com;
+        set $MAGE_ROOT <MY_MAGENTO_WEBROOT>;
+        index index.php;
+        root $MAGE_ROOT/pub;
+        set $MAGE_CODE default;
+        location / {
+                try_files $uri $uri/ /index.php$is_args$args;
+        }
+        include /etc/nginx/defaults/magento2.conf;
+}
+server {
+        listen 80;
+        server_name myotherdomain.com;
+        set $MAGE_ROOT <MY_MAGENTO_WEBROOT>;
+        index index.php;
+        root $MAGE_ROOT/pub;
+        set $MAGE_CODE other;
+        location / {
+                try_files $uri $uri/ /index.php$is_args$args;
+        }
+        include /etc/nginx/defaults/magento2.conf;
+}
+```
+
+![Magento Exam Question](./images/icon-question.png)**How do you set up a new subfolder Website?**
+
+![Magento Exam Information](./images/icon-info.png)For the purpose of this question we shall assume you are running an Nginx Webserver with PHP-FPM and will specifically focus on the multi-website aspect of the configuration.
+
+```perl
+server {
+    listen 80;
+    server_name mydomain.com;
+    set $MAGE_ROOT <MY_MAGENTO_WEBROOT>;
+    index index.php;
+    root $MAGE_ROOT/pub;
+
+    location /cn/ {
+        set $code my_project_cn_store;
+        rewrite / /cn/index.php;
+        try_files $uri $uri/ /cn/index.php$is_args$args;
+    }
+
+    location /us/ {
+        set $code my_project_us_store;
+        rewrite / /us/index.php;
+        try_files $uri $uri/ /us/index.php$is_args$args;
+    }
+
+    location / {
+        set $code default;
+        try_files $uri $uri/ /index.php$is_args$args;
+    }
+
+    include /etc/nginx/defaults/magento2.conf;
+}
+```
+
+`/pub/us/index.php`
+```php
+<?php
+
+use Magento\Framework\App\Bootstrap;
+use Magento\Framework\App\Filesystem\DirectoryList;
+
+try {
+    require __DIR__ . '/../../app/bootstrap.php';
+} catch (\Exception $e) {
+    echo
+<<<HTML
+    <div style="font:12px/1.35em arial, helvetica, sans-serif;">
+        <div style="margin:0 0 25px 0; border-bottom:1px solid #ccc;">
+            <h3 style="margin:0;font-size:1.7em;font-weight:normal;text-transform:none;text-align:left;color:#2f2f2f;">Autoload error</h3>
+        </div>
+        <p>{$e->getMessage()}</p>
+    </div>
+HTML;
+    exit(1);
+}
+$params = $_SERVER;
+$params[\Magento\Store\Model\StoreManager::PARAM_RUN_CODE] = 'my_project_us_website';
+$params[\Magento\Store\Model\StoreManager::PARAM_RUN_TYPE] = 'website';
+$params[Bootstrap::INIT_PARAM_FILESYSTEM_DIR_PATHS] = [
+    DirectoryList::PUB => [DirectoryList::URL_PATH => ''],
+    DirectoryList::MEDIA => [DirectoryList::URL_PATH => 'media'],
+    DirectoryList::STATIC_VIEW => [DirectoryList::URL_PATH => 'static'],
+    DirectoryList::UPLOAD => [DirectoryList::URL_PATH => 'media/upload'],
+];
+$bootstrap = Magento\Framework\App\Bootstrap::create(BP, $params);
+
+/** @var Magento\Framework\App\Http $app */
+$app = $bootstrap->createApplication(Magento\Framework\App\Http::class);
+$bootstrap->run($app);
+
+```
+
+![Magento Exam Information](./images/icon-info.png)'`my_project_us_website`'; must match the Website code in Admin > Stores > All Stores
+
+![Magento Exam Information](./images/icon-info.png)'`my_project_us_store`'; must match the Store code in Admin > Stores > All Stores
\ No newline at end of file
diff --git a/12.Magento-Index-Management.md b/12.Magento-Index-Management.md
new file mode 100755
index 0000000..bb1872f
--- /dev/null
+++ b/12.Magento-Index-Management.md
@@ -0,0 +1,1160 @@
+12 - Index Management
+=====================
+
+![Magento Exam Question](./images/icon-question.png)**Describe Index Management. How would you create your own Indexer?**
+
+> An index collects, parses and stores data to facilitate fast and accurate information retrieval which saves repeatedly making complex calculations. Magento utilities indexers due to its wide range of features and complex/large data sets.
+>
+> By default Magento indexes the following:
+
+*   Product Prices
+*   Product Inventory
+*   Product Attribute Data
+*   Product Category Associations
+
+![Magento Exam Information](./images/icon-info.png)Indexer could be considered a form of [caching](#h.s3rfn71t3q6i) but, where data is transformed during the process.
+
+![Magento Exam Information](./images/icon-info.png)[Excellent Indexer Guide Here](https://docs.google.com/presentation/d/e/2PACX-1vRQioOtIvVz8WGa5XTOGmWsu0t6rjUhDQdUGdmss62YZuTJSEV1lwkefBRKGKKxSFTA5k2P5oki_A2t/pub%23slide%3Did.g587a946c8a_2_51&sa=D&ust=1609223266338000&usg=AOvVaw0ceVngmq-G5XpF5QnfZXbi)
+
+> Creating an indexer
+
+> The structure of an indexer might look something like:
+
+![](./images/Magento-2-Exam-Notes-Example-Indexer.png)
+
+> Only the necessaries will be covered here:
+
+#### `indexer.xml`
+
+```xml
+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Indexer/etc/indexer.xsd">
+    <indexer id="example_entity" view_id="example_entity" class="MyVendor\MyModule\Model\Indexer\Example\Index" shared_index="catalog_product_price">
+        <title translate="true">An Example Indexer</title>
+        <description translate="true">An example indexer for the purpose of the Magento exam notes</description>
+    </indexer>
+</config>
+```
+
+| Attribute | Required | Description |
+| --- | --- | --- |
+| `id` | Yes | A unique indexer ID |
+| `class` | No | The class that processes indexer methods (executeFull, executeList, executeRow) |
+| `primary` | No | The source provider |
+| `shared_index` | No | Use this option to improve performance if your indexer is related to another indexer. In this example, if the Catalog Product Price index needs to be reindexed |
+| `view_id` | No | The ID of the view element that is defined in the mview.xml configuration file. |
+
+
+> An indexer process can also have the following optional parameters:
+
+| Parameter | Description |
+| --- | --- |
+| `description` | The description of indexer to be displayed on the System > Tools > Index Management page. |
+| `fieldset` | Describes the fields, source, and data provider of the flat index table. |
+| `saveHandler` | An extension point. The class for processing (deleting, saving, updating) items when indexing. |
+| `structure` |  The class that processes (creates, removes) flat index tables. |
+| `title` | The title of indexer to be displayed on the System > Tools > Index Management page. |
+
+#### `mview.xml`
+
+> Add the `mview.xml` configuration file in the etc module directory, where you declare the following:
+
+*   Indexer view ID
+*   Indexer class
+*   The database tables the indexer tracks
+*   What column data is sent to the indexer
+
+
+> All Mview declarations related to a module should be declared in one file.
+
+```xml
+<?xml version="1.0" encoding="UTF-8"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Mview/etc/mview.xsd">
+    <view id="example_entity" class="MyVendor\MyModule\Model\Indexer\Example\Index" group="indexer">
+        <subscriptions>
+            <table name="catalog_product_entity" entity_column="entity_id" />
+            <table name="catalog_product_entity_int" entity_column="entity_id" />
+            <table name="catalog_product_entity_text" entity_column="entity_id" />
+            <table name="catalog_product_entity_decimal" entity_column="entity_id" />
+            <table name="catalog_product_entity_varchar" entity_column="entity_id" />
+        </subscriptions>
+    </view>
+</config>
+```
+
+| Attribute | Required | Description |
+| `view` | Yes | The new materialized view to be declared of which have attributes: `id` = the ID of this new view. `class` = The model class object to call. `group` = Which CRON group this falls under (usually indexer).|
+| `subscriptions` | No |  This places database triggers for your new view when the following tables are updated. `<subscriptions>` take: `<table>` - `name` = The name of the table, `entity_column` =  that table's entity ID column to use. |
+
+> `MyVendor\MyModule\Model\Indexer\Example\Index`
+
+> The main indexer class implements the following interfaces:
+
+*   `Magento\Framework\Mview\ActionInterface`
+*   `Magento\Framework\Indexer\ActionInterface`
+
+> And therefore must have the following methods:
+
+*   `execute` - Used by mview, allows process indexer in the "Update on schedule" mode
+*   `executeFull` - Will take all of the data and reindex Will run when reindex via command line or [Update on Save](#h.wndwlsqudpgx). Should take into account all entities in the system.
+*   `executeList` - Works with a set of entity changed (may be massaction)
+*   `executeRow` - Works in runtime for a single entity using plugins ([Update On Schedule](#h.n9r64sdphflm)).
+
+![Magento Exam Information](./images/icon-info.png)Only need to remember this, the following is for demonstration purposes only.
+
+Example:
+```php
+<?php
+
+namespace MyVendor\MyModule\Model\Indexer\Example;
+
+use Magento\Framework\App\ObjectManager;
+use Magento\Framework\Indexer\CacheContext;
+use Magento\Framework\Indexer\IndexerRegistry;
+use Magento\Framework\Mview\ActionInterface as MviewActionInterface;
+use Magento\Framework\Indexer\ActionInterface as IndexerActionInterface;
+use MyVendor\MyModule\Api\Data\ExampleInterface;
+
+class Index implements MviewActionInterface, IndexerActionInterface
+{
+    /**
+     * Indexer ID in configuration
+     * @var string
+     */
+    const INDEXER_ID = 'my_indexer';
+
+    /**
+     * Indexer main table
+     * @var string
+     */
+    const BLOG_PRODUCT_POST_INDEX_TABLE = 'my_indexer_idx';
+
+    /**
+     * Indexer temporary table for dimension
+     * @var string
+     */
+    const BLOG_PRODUCT_POST_TMP_TABLE = 'my_indexer_tmp';
+
+    /**
+     * @var CacheContext
+     * @since 1.0.1
+     */
+    protected $cacheContext;
+
+    /** @var Example\Action\FullFactory */
+    protected $fullActionFactory;
+
+    /** @var Example\Action\RowsFactory */
+    protected $rowsActionFactory;
+
+    /** @var IndexerRegistry */
+    protected $indexerRegistry;
+
+    /**
+     * @param Example\Action\FullFactory $fullActionFactory
+     * @param Example\Action\RowsFactory $rowsActionFactory
+     * @param IndexerRegistry $indexerRegistry
+     */
+    public function __construct(
+        Example\Action\FullFactory $fullActionFactory,
+        Example\Action\RowsFactory $rowsActionFactory,
+        IndexerRegistry $indexerRegistry
+    ) {
+        $this->fullActionFactory = $fullActionFactory;
+        $this->rowsActionFactory = $rowsActionFactory;
+        $this->indexerRegistry = $indexerRegistry;
+    }
+
+    /**
+     * Used by mview, allows process indexer in the "Update on schedule" mode
+     */
+    public function execute($ids)
+    {
+        // Used by mview, allows you to process multiple blog posts in the "Update on schedule" mode
+        $this->executeAction($ids);
+        $this->registerEntities($ids);
+    }
+
+    /**
+     * Will take all of the data and reindex
+     * Will run when reindex via command line
+     * Should take into account all blog posts in the system
+     */
+    public function executeFull()
+    {
+        /** @var Example\Action\Full $action */
+        $action = $this->fullActionFactory->create();
+        $action->execute();
+        $this->registerTags();
+    }
+
+    /**
+     * Works with a set of entity changed (may be massaction)
+     */
+    public function executeList(array $ids)
+    {
+        // Works with a set of blog posts (mass actions and so on)
+        $this->executeAction($ids);
+    }
+
+    /**
+     * Works in runtime for a single entity using plugins
+     */
+    public function executeRow($id)
+    {
+        // Works in runtime for a single blog post using plugins
+        $this->executeAction([$id]);
+    }
+
+    /**
+     * Add entities to cache context
+     * @param int[] $ids
+     * @return void
+     * @since 1.0.1
+     */
+    protected function registerEntities($ids)
+    {
+        $this->getCacheContext()->registerEntities(ExampleInterface::CACHE_TAG, $ids);
+    }
+
+    /**
+     * Add tags to cache context
+     * @return void
+     * @since 1.0.1
+     */
+    protected function registerTags()
+    {
+        $this->getCacheContext()->registerTags([ExampleInterface::CACHE_TAG]);
+    }
+
+    /**
+     * Execute action for single entity or list of entities
+     * @param int[] $ids
+     * @return $this
+     */
+    protected function executeAction($ids)
+    {
+        $ids = array_unique($ids);
+        $indexer = $this->indexerRegistry->get(static::INDEXER_ID);
+
+        /** @var Example\Action\Rows $action */
+        $action = $this->rowsActionFactory->create();
+        if ($indexer->isWorking()) {
+            $action->execute($ids, true);
+        }
+        $action->execute($ids);
+
+        return $this;
+    }
+
+    /**
+     * Get cache context
+     * @return CacheContext
+     * @since 1.0.1
+     */
+    protected function getCacheContext(): CacheContext
+    {
+        if (!($this->cacheContext instanceof CacheContext)) {
+            return ObjectManager::getInstance()->get(CacheContext::class);
+        } else {
+            return $this->cacheContext;
+        }
+    }
+}
+```
+
+> In this example, Full reindexes and Row indexes have been separated into their own object
+
+
+`MyVendor\MyModule\Model\Indexer\Example\Action\Full`
+```php
+
+
+
+<?php
+
+declare(strict_types=1);
+
+namespace MyVendor\MyModule\Model\Indexer\Example\Action;
+
+use Magento\Indexer\Model\ProcessManager;
+use Magento\Store\Model\Store;
+use Magento\Catalog\Model\Config;
+use Magento\Catalog\Model\Product;
+use Magento\Framework\DB\Select;
+use Magento\Framework\App\ObjectManager;
+use Magento\Framework\EntityManager\MetadataPool;
+use Magento\Framework\Indexer\BatchProviderInterface;
+use Magento\Framework\Exception\CouldNotSaveException;
+use Magento\Framework\Exception\CouldNotDeleteException;
+use Magento\Framework\DB\Query\Generator as QueryGenerator;
+use MyVendor\MyModule\Helper\Data as Helper;
+use MyVendor\MyModule\Api\Data\ExampleInterface;
+use MyVendor\MyModule\Model\Indexer\Example\AbstractAction;
+use MyVendor\MyModule\Model\Indexer\Example\TableMaintainer;
+use MyVendor\MyModule\Model\ResourceModel\Example as ResourceModel;
+
+/**
+ * Class Full reindex action
+ * @SuppressWarnings(PHPMD.CouplingBetweenObjects)
+ */
+class Full extends AbstractAction
+{
+    /**
+     * Row count to process in a batch
+     * @var int
+     */
+    private $batchRowsCount;
+
+    /** @var Config */
+    protected $config;
+
+    /** @var BatchProviderInterface */
+    private $batchProvider;
+
+    /**
+     * @param Config $config
+     * @param Helper $helper
+     * @param ResourceModel $resource
+     * @param TableMaintainer $tableMaintainer
+     * @param QueryGenerator|null $queryGenerator
+     * @param BatchProviderInterface|null $batchProvider
+     * @param MetadataPool|null $metadataPool
+     * @param int|null $batchRowsCount
+     * @param ProcessManager $processManager
+     * @SuppressWarnings(PHPMD.ExcessiveParameterList)
+     */
+    public function __construct(
+        Config $config,
+        Helper $helper,
+        ResourceModel $resource,
+        TableMaintainer $tableMaintainer,
+        QueryGenerator $queryGenerator = null,
+        BatchProviderInterface $batchProvider = null,
+        MetadataPool $metadataPool = null,
+        $batchRowsCount = null,
+        ProcessManager $processManager = null
+    ) {
+        parent::__construct(
+            $config,
+            $helper,
+            $resource,
+            $tableMaintainer,
+            $queryGenerator,
+            $metadataPool,
+            $processManager
+        );
+        $objectManager = ObjectManager::getInstance();
+        $this->batchRowsCount = $batchRowsCount;
+        $this->batchProvider = $batchProvider ?: $objectManager->get(BatchProviderInterface::class);
+    }
+
+    /** {@inheritdoc} */
+    public function execute(array $entityIds = [], bool $useTmpTables = false): AbstractAction
+    {
+        if ($this->isEnabled()) {
+            $userFunctions = [];
+            // $this->createTables();
+            foreach ($this->storeManager->getStores() as $store) {
+                $userFunctions[$store->getId()] = function () use ($store) {
+                    if ($this->getIndexTable((int) $store->getId()) !== $this->resource->getMainTable()) {
+                        $batchCount = ($this->batchRowsCount && is_array($this->batchRowsCount) && isset($this->batchRowsCount["configurable"]))
+                            ? (int) $this->batchRowsCount["configurable"]
+                            : static::RANGE_PRODUCT_STEP;
+
+                        $batchQueries = $this->prepareSelectsByRange(
+                            $this->getAllProducts($store),
+                            ExampleInterface::ENTITY_COLUMN_PRODUCT_ID,
+                            $batchCount
+                        );
+
+                        /** @var Select $select */
+                        foreach ($batchQueries as $select) {
+                            if (!empty($entityIds)) {
+                                $select->where(
+                                    $this->connection->prepareSqlCondition(
+                                        'aw.' . ExampleInterface::ENTITY_COLUMN_PRODUCT_ID,
+                                        ['in' => $entityIds]
+                                    )
+                                );
+                            }
+                            $products = $this->connection->fetchAll($select);
+                            if ($products && is_array($products) && !empty($products)) {
+                                foreach ($products as $product) {
+                                    $this->reindex($store, $product);
+                                }
+                            }
+                        }
+                    } else {
+                        print(__("Performing full re-index as queues are empty... Please wait a while." . PHP_EOL));
+                        $products = $this->connection->fetchAll($this->getAllProducts($store));
+                        if ($products && is_array($products) && !empty($products)) {
+                            foreach ($products as $product) {
+                                $this->reindex($store, $product);
+                            }
+                        }
+                    }
+                };
+            }
+            $this->processManager->execute($userFunctions);
+        } else {
+            $this->logger->warning(
+                __("[%1] WARNING: will not reindex, module is disabled", static::class)
+            );
+        }
+
+        return $this;
+    }
+
+    /** {@inheritdoc} */
+    protected function reindex(Store $store, array $postExampleData): void
+    {
+        $action = 'update/insert';
+        $rowsAffected = 0;
+        if (
+            !isset($postExampleData[ExampleInterface::ENTITY_COLUMN_PRODUCT_ID])
+            || !isset($postExampleData[ExampleInterface::ENTITY_COLUMN_BLOG_POST_ID])
+            || !isset($postExampleData[ExampleInterface::ENTITY_COLUMN_STORE_ID])
+        ) {
+            return;
+        }
+
+        /** @var Product $product */
+        $product = $this->productRepository->getById($postExampleData[ExampleInterface::ENTITY_COLUMN_PRODUCT_ID]);
+        $postExampleData[ExampleInterface::ENTITY_COLUMN_PRICE] = $this->calculateProductPrice($product);
+        $postExampleData[ExampleInterface::ENTITY_COLUMN_URL] = $product->getProductUrl();
+        $postExampleData[ExampleInterface::ENTITY_COLUMN_IS_AVAILABLE] = $product->isAvailable();
+        $postExampleData[ExampleInterface::ENTITY_COLUMN_IMAGE_URL] = $this->getProductImageFullUrl($product);
+
+        $select = $this->resource->getConnection()
+            ->select()
+            ->from($this->resource->getMainTable())
+            ->where(
+                $this->resource->getConnection()->prepareSqlCondition(
+                    ExampleInterface::ENTITY_COLUMN_PRODUCT_ID,
+                    ['eq' => $postExampleData[ExampleInterface::ENTITY_COLUMN_PRODUCT_ID]]
+                )
+            )->where(
+                $this->resource->getConnection()->prepareSqlCondition(
+                    ExampleInterface::ENTITY_COLUMN_BLOG_POST_ID,
+                    ['eq' => $postExampleData[ExampleInterface::ENTITY_COLUMN_BLOG_POST_ID]]
+                )
+            )->where(
+                $this->resource->getConnection()->prepareSqlCondition(
+                    ExampleInterface::ENTITY_COLUMN_STORE_ID,
+                    ['eq' => (int)$postExampleData[ExampleInterface::ENTITY_COLUMN_STORE_ID]]
+                )
+            );
+
+        $postExample = $this->resource->getConnection()->fetchRow($select);
+        if ($postExample) {
+            $action = 'update';
+            $rowsAffected = (int)$this->resource->getConnection()->update(
+                $this->resource->getMainTable(),
+                $postExampleData,
+                [
+                    ExampleInterface::ENTITY_COLUMN_PRODUCT_ID . ' = ?' => (int)$postExampleData[ExampleInterface::ENTITY_COLUMN_PRODUCT_ID],
+                    ExampleInterface::ENTITY_COLUMN_BLOG_POST_ID . ' = ?' => (int)$postExampleData[ExampleInterface::ENTITY_COLUMN_BLOG_POST_ID],
+                    ExampleInterface::ENTITY_COLUMN_STORE_ID . ' = ?' => (int)$postExampleData[ExampleInterface::ENTITY_COLUMN_STORE_ID]
+
+                ]
+            );
+            $rowsAffected = ($rowsAffected === 0) ? 1 : $rowsAffected; // Updates don't always change rows if the data is the same, for by-pass CouldNotSaveException here.
+        } else {
+            $action = 'insert';
+            $rowsAffected = (int)$this->resource->getConnection()->insert(
+                $this->resource->getMainTable(),
+                $postExampleData
+            );
+        }
+
+        if ($rowsAffected === 0) {
+            throw new CouldNotSaveException(
+                __(
+                    "[%1] ERROR: Could not %2 Post Related Product %3 for Post %4 of Store %5",
+                    static::class,
+                    $action,
+                    (int)$postExampleData[ExampleInterface::ENTITY_COLUMN_PRODUCT_ID],
+                    (int)$postExampleData[ExampleInterface::ENTITY_COLUMN_BLOG_POST_ID],
+                    (int)$postExampleData[ExampleInterface::ENTITY_COLUMN_STORE_ID]
+                )
+            );
+        } else if (
+            $this->removeIndexEntry(
+                (int)$postExampleData[ExampleInterface::ENTITY_COLUMN_STORE_ID],
+                (int)$postExampleData[ExampleInterface::ENTITY_COLUMN_BLOG_POST_ID],
+                (int)$postExampleData[ExampleInterface::ENTITY_COLUMN_PRODUCT_ID]
+            ) === 0
+        ) {
+            $this->logger->warning(
+                __(
+                    "[%1] WARNING: Could not remove Post Related Product %2 for Post %3 of Store %4",
+                    static::class,
+                    (int)$postExampleData[ExampleInterface::ENTITY_COLUMN_PRODUCT_ID],
+                    (int)$postExampleData[ExampleInterface::ENTITY_COLUMN_BLOG_POST_ID],
+                    (int)$postExampleData[ExampleInterface::ENTITY_COLUMN_STORE_ID]
+                )
+            );
+        }
+    }
+
+    /**
+     * Create the store tables
+     * @todo add tableMaintainer functionality for dimension
+     * @return void
+     */
+    private function createTables(): void
+    {
+        foreach ($this->storeManager->getStores() as $store) {
+            $this->tableMaintainer->createTablesForStore((int)$store->getId());
+        }
+    }
+}
+```
+
+`MyVendor\MyModule\Model\Indexer\Example\Action\Rows`
+```php
+<?php
+
+namespace MyVendor\MyModule\Model\Indexer\Example\Action;
+
+use Magento\Store\Model\Store;
+use Magento\Catalog\Model\Product;
+use Magento\Framework\Exception\CouldNotSaveException;
+use Magento\Framework\Exception\CouldNotDeleteException;
+use MyVendor\MyModule\Api\Data\ExampleInterface;
+use MyVendor\MyModule\Model\Indexer\Example\AbstractAction;
+
+class Rows extends AbstractAction
+{
+    /** {@inheritdoc} */
+    public function execute(array $entityIds = [], bool $useTmpTables = false): AbstractAction
+    {
+        if ($this->isEnabled()) {
+            $userFunctions = [];
+            foreach ($this->storeManager->getStores() as $store) {
+                $userFunctions[$store->getId()] = function () use ($store, $entityIds) {
+
+                    $select = $this->getAllProducts($store);
+                    $select->where(
+                        $this->connection->prepareSqlCondition(
+                            'aw.' . ExampleInterface::ENTITY_COLUMN_PRODUCT_ID,
+                            ['in' => $entityIds]
+                        )
+                    );
+                    $products = $this->connection->fetchAll($select);
+                    if ($products && is_array($products) && !empty($products)) {
+                        foreach ($products as $product) {
+                            $this->reindex($store, $product);
+                        }
+                    }
+                };
+            }
+
+            $this->processManager->execute($userFunctions);
+        } else {
+            $this->logger->warning(
+                __("[%1] WARNING: will not reindex, module is disabled", static::class)
+            );
+        }
+        return $this;
+    }
+
+    /** {@inheritdoc} */
+    protected function reindex(Store $store, array $postExampleData): void
+    {
+        $action = 'update/insert';
+        $rowsAffected = 0;
+        if (
+            !isset($postExampleData[ExampleInterface::ENTITY_COLUMN_PRODUCT_ID])
+            || !isset($postExampleData[ExampleInterface::ENTITY_COLUMN_BLOG_POST_ID])
+            || !isset($postExampleData[ExampleInterface::ENTITY_COLUMN_STORE_ID])
+        ) {
+            return;
+        }
+
+        /** @var Product $product */
+        $product = $this->productRepository->getById($postExampleData[ExampleInterface::ENTITY_COLUMN_PRODUCT_ID]);
+        $postExampleData[ExampleInterface::ENTITY_COLUMN_PRICE] = $this->calculateProductPrice($product);
+        $postExampleData[ExampleInterface::ENTITY_COLUMN_URL] = $product->getProductUrl();
+        $postExampleData[ExampleInterface::ENTITY_COLUMN_IS_AVAILABLE] = $product->isAvailable();
+        $postExampleData[ExampleInterface::ENTITY_COLUMN_IMAGE_URL] = $this->getProductImageFullUrl($product);
+
+        $select = $this->resource->getConnection()
+            ->select()
+            ->from($this->resource->getMainTable())
+            ->where(
+                $this->resource->getConnection()->prepareSqlCondition(
+                    ExampleInterface::ENTITY_COLUMN_PRODUCT_ID,
+                    ['eq' => $postExampleData[ExampleInterface::ENTITY_COLUMN_PRODUCT_ID]]
+                )
+            )->where(
+                $this->resource->getConnection()->prepareSqlCondition(
+                    ExampleInterface::ENTITY_COLUMN_BLOG_POST_ID,
+                    ['eq' => $postExampleData[ExampleInterface::ENTITY_COLUMN_BLOG_POST_ID]]
+                )
+            )->where(
+                $this->resource->getConnection()->prepareSqlCondition(
+                    ExampleInterface::ENTITY_COLUMN_STORE_ID,
+                    ['eq' => (int)$postExampleData[ExampleInterface::ENTITY_COLUMN_STORE_ID]]
+                )
+            );
+
+        $postExample = $this->resource->getConnection()->fetchRow($select);
+        if ($postExample) {
+            $action = 'update';
+            $rowsAffected = (int)$this->resource->getConnection()->update(
+                $this->resource->getMainTable(),
+                $postExampleData,
+                [
+                    ExampleInterface::ENTITY_COLUMN_PRODUCT_ID . ' = ?' => (int)$postExampleData[ExampleInterface::ENTITY_COLUMN_PRODUCT_ID],
+                    ExampleInterface::ENTITY_COLUMN_BLOG_POST_ID . ' = ?' => (int)$postExampleData[ExampleInterface::ENTITY_COLUMN_BLOG_POST_ID],
+                    ExampleInterface::ENTITY_COLUMN_STORE_ID . ' = ?' => (int)$postExampleData[ExampleInterface::ENTITY_COLUMN_STORE_ID]
+
+                ]
+            );
+            $rowsAffected = ($rowsAffected === 0) ? 1 : $rowsAffected; // Updates don't always change rows if the data is the same, for by-pass CouldNotSaveException here.
+        } else {
+            $action = 'insert';
+            $rowsAffected = (int)$this->resource->getConnection()->insert(
+                $this->resource->getMainTable(),
+                $postExampleData
+            );
+        }
+
+        if ($rowsAffected === 0) {
+            throw new CouldNotSaveException(
+                __(
+                    "[%1] ERROR: Could not %2 Post Related Product %3 for Post %4 of Store %5",
+                    static::class,
+                    $action,
+                    (int)$postExampleData[ExampleInterface::ENTITY_COLUMN_PRODUCT_ID],
+                    (int)$postExampleData[ExampleInterface::ENTITY_COLUMN_BLOG_POST_ID],
+                    (int)$postExampleData[ExampleInterface::ENTITY_COLUMN_STORE_ID]
+                )
+            );
+        } else if (
+            $this->removeIndexEntry(
+                (int)$postExampleData[ExampleInterface::ENTITY_COLUMN_STORE_ID],
+                (int)$postExampleData[ExampleInterface::ENTITY_COLUMN_BLOG_POST_ID],
+                (int)$postExampleData[ExampleInterface::ENTITY_COLUMN_PRODUCT_ID]
+            ) === 0
+        ) {
+            throw new CouldNotDeleteException(
+                __(
+                    "[%1] ERROR: Could not remove Post Related Product %2 for Post %3 of Store %4",
+                    static::class,
+                    (int)$postExampleData[ExampleInterface::ENTITY_COLUMN_PRODUCT_ID],
+                    (int)$postExampleData[ExampleInterface::ENTITY_COLUMN_BLOG_POST_ID],
+                    (int)$postExampleData[ExampleInterface::ENTITY_COLUMN_STORE_ID]
+                )
+            );
+        }
+    }
+
+    /** {@inheritdoc} */
+    protected function isRangingNeeded(): bool
+    {
+        return false;
+    }
+}
+```
+
+`MyVendor\MyModule\Model\Indexer\Example\AbstractAction`
+```php
+<?php
+
+namespace MyVendor\MyModule\Model\Indexer\Example;
+
+use Exception;
+use Zend_Db_Expr;
+use Psr\Log\LoggerInterface;
+use Magento\Store\Model\Store;
+use Magento\Store\Model\StoreManagerInterface;
+use Magento\Catalog\Model\Config;
+use Magento\Catalog\Model\Product;
+use Magento\Catalog\Helper\ImageFactory;
+use Magento\Catalog\Model\Product\Visibility;
+use Magento\Catalog\Api\Data\ProductInterface;
+use Magento\GroupedProduct\Model\Product\Type\Grouped;
+use Magento\ConfigurableProduct\Model\Product\Type\Configurable;
+use Magento\Bundle\Model\Product\Type as Bundle;
+use Magento\Catalog\Api\ProductRepositoryInterface;
+use Magento\Catalog\Model\Product\Attribute\Source\Status;
+use Magento\Indexer\Model\ProcessManager;
+use Magento\Framework\DB\Select;
+use Magento\Framework\App\ObjectManager;
+use Magento\Framework\EntityManager\MetadataPool;
+use Magento\Framework\DB\Adapter\AdapterInterface;
+use Magento\Framework\DB\Query\BatchIteratorInterface;
+use Magento\Framework\Exception\CouldNotSaveException;
+use Magento\Framework\Exception\CouldNotDeleteException;
+use Magento\Framework\DB\Query\Generator as QueryGenerator;
+use MyVendor\MyModule\Api\Data\ExampleInterface;
+use MyVendor\MyModule\Helper\Data as Helper;
+use MyVendor\MyModule\Model\Indexer\Example\TableMaintainer;
+use MyVendor\MyModule\Model\ResourceModel\Example as ResourceModel;
+
+/**
+ * Class AbstractAction
+ * @api
+ * @SuppressWarnings(PHPMD.CouplingBetweenObjects)
+ * @since 1.0.1
+ */
+abstract class AbstractAction
+{
+    /**
+     * Chunk size for product
+     * @var int
+     */
+    const RANGE_PRODUCT_STEP = 1000000;
+
+    /**
+     * The old Aheadworks Blog Post Related Products index table name
+     * @var string
+     */
+    const INDEXER_NAME = 'example_entity';
+
+    /**
+     * The new main Blog Post Related Products index table name
+     * @var string
+     */
+    const MAIN_INDEX_TABLE = 'example_entity_idx';
+
+    /**
+     * Index table column Product ID
+     * @var string
+     */
+    const COLUMN_PRODUCT_ID = 'product_id';
+
+    /**
+     * Index table column Blog Post ID
+     * @var string
+     */
+    const COLUMN_POST_ID = 'post_id';
+
+    /**
+     * Index table column Store ID
+     * @var string
+     */
+    const COLUMN_STORE_ID = 'store_id';
+
+    /**
+     * Cached all product select by store id
+     * @var Select[]
+     */
+    protected $productsSelects = [];
+
+    /** @var MetadataPool */
+    protected $metadataPool;
+
+    /** @var LoggerInterface */
+    protected $logger;
+
+    /** @var TableMaintainer */
+    protected $tableMaintainer;
+
+    /** @var ResourceModel */
+    protected $resource;
+
+    /** @var StoreManagerInterface */
+    protected $storeManager;
+
+    /** @var AdapterInterface */
+    protected $connection;
+
+    /** @var QueryGenerator */
+    protected $queryGenerator;
+
+    /** @var Config */
+    protected $config;
+
+    /** @var ImageFactory */
+    protected $imageHelperFactory;
+
+    /** @var ProductRepositoryInterface */
+    protected $productRepository;
+
+    /** @var ProcessManager */
+    protected $processManager;
+
+    /** @var Helper */
+    protected $helper;
+
+    /**
+     * @param Config $config
+     * @param Helper $helper
+     * @param ResourceModel $resource
+     * @param TableMaintainer $tableMaintainer
+     * @param QueryGenerator|null $queryGenerator
+     * @param MetadataPool|null $metadataPool
+     * @param ProcessManager|null $processManager
+     */
+    public function __construct(
+        Config $config,
+        Helper $helper,
+        ResourceModel $resource,
+        TableMaintainer $tableMaintainer,
+        QueryGenerator $queryGenerator = null,
+        MetadataPool $metadataPool = null,
+        ProcessManager $processManager = null
+    ) {
+        $this->config = $config;
+        $this->helper = $helper;
+        $this->resource = $resource;
+        $this->tableMaintainer = $tableMaintainer;
+        $this->logger = $this->helper->getLogger();
+        $this->connection = $resource->getConnection();
+        $this->storeManager = $this->helper->getStoreManager();
+        $this->productRepository = $this->helper->createProductRepository();
+        $this->queryGenerator = $queryGenerator ?: ObjectManager::getInstance()->get(QueryGenerator::class);
+        $this->metadataPool = $metadataPool ?: ObjectManager::getInstance()->get(MetadataPool::class);
+        $this->processManager = $processManager ?: ObjectManager::getInstance()->get(ProcessManager::class);
+    }
+
+    /**
+     * Run full reindex
+     * @param array $entityIds
+     * @param bool $useTmpTables
+     * @return $this
+     */
+    abstract public function execute(array $entityIds = [], bool $useTmpTables = false): AbstractAction;
+
+    /**
+     * Run reindexation
+     * @param Store $store
+     * @param array $postExampleData
+     * @return void
+     * @throws CouldNotSaveException
+     * @throws CouldNotDeleteException
+     */
+    abstract protected function reindex(Store $store, array $postExampleData): void;
+
+    /**
+     * Return validated table name
+     * @param string|string[] $table
+     * @return string
+     */
+    protected function getTable($table)
+    {
+        return $this->resource->getTable($table);
+    }
+
+    /**
+     * Return the relvent index table name to work from. Since we are re-writing the current blog indexers,
+     * this depends on a number of factors: if the old index table still has rows then use this, else use the
+     * new. If new is empty and we are fully re-indexing, get main entity table.
+     * @todo Temp tables, Table maintainer
+     * @param int $storeId
+     * @return string
+     * @since 1.0.1
+     */
+    protected function getIndexTable(int $storeId): string
+    {
+        $conn = $this->connection;
+        $t = $conn->getTableName(static::MAIN_INDEX_TABLE);
+        if ($this->areTempTablesNeeded()) {
+            $t = $this->tableMaintainer->getMainReplicaTable($storeId);
+        } else if ($this->isTableMaintainerNeeded()) {
+            $t = $this->tableMaintainer->getMainTable($storeId);
+        }
+        return $t;
+    }
+
+    /** @return bool */
+    protected function isEnabled(): bool
+    {
+        return $this->helper->isEnabled();
+    }
+
+    /** @return mixed */
+    protected function getConfigValue(string $configField, string $scope = null)
+    {
+        return $this->helper->getConfigValue($configField, $scope);
+    }
+
+    /**
+     * Check whether select ranging is needed
+     * @return bool
+     */
+    protected function isRangingNeeded(): bool
+    {
+        return true;
+    }
+
+    /**
+     * Check whether select ranging is needed
+     * @todo add functionality to handle this
+     * @return bool
+     */
+    protected function areTempTablesNeeded(): bool
+    {
+        return false;
+    }
+
+    /**
+     * Check whether multiple tables for multiple stores is needed
+     * @todo add functionality to handle this
+     * @return bool
+     */
+    protected function isTableMaintainerNeeded(): bool
+    {
+        return false;
+    }
+
+    /**
+     * Return selects cut by min and max
+     * @param Select $select
+     * @param string $field
+     * @param int $range
+     * @return Select[]
+     */
+    protected function prepareSelectsByRange(
+        Select $select,
+        string $field,
+        int $range = self::RANGE_PRODUCT_STEP
+    ) {
+        if ($this->isRangingNeeded()) {
+            $iterator = $this->queryGenerator->generate(
+                $field,
+                $select,
+                $range,
+                BatchIteratorInterface::NON_UNIQUE_FIELD_ITERATOR
+            );
+
+            $queries = [];
+            foreach ($iterator as $query) {
+                $queries[] = $query;
+            }
+            return $queries;
+        }
+        return [$select];
+    }
+
+    /**
+     * Get select for all products
+     * @param Store $store
+     * @return Select
+     * @throws Exception when metadata not found for ProductInterface
+     */
+    protected function getAllProducts(Store $store)
+    {
+        if (!isset($this->productsSelects[$store->getId()])) {
+            $table = $this->getIndexTable($store->getId());
+            $statusAttributeId = $this->config->getAttribute(Product::ENTITY, 'status')->getId();
+            $visibilityAttributeId = $this->config->getAttribute(Product::ENTITY, 'visibility')->getId();
+            $nameAttributeId = $this->config->getAttribute(Product::ENTITY, 'name')->getId();
+            $priceAttributeId = $this->config->getAttribute(Product::ENTITY, 'price')->getId();
+            $urlAttributeId = $this->config->getAttribute(Product::ENTITY, 'url_key')->getId();
+            $imgAttributeId = $this->config->getAttribute(Product::ENTITY, 'image')->getId();
+            $metadata = $this->metadataPool->getMetadata(ProductInterface::class);
+            $linkField = $metadata->getLinkField();
+            $blogPostColumn = ($table === $this->resource->getMainTable())
+                ? ExampleInterface::ENTITY_COLUMN_BLOG_POST_ID
+                : static::COLUMN_POST_ID;
+
+            $select = $this->connection
+                ->select()
+                ->from(
+                    ['aw' => $table],
+                    []
+                )->joinLeft(
+                    ['cp' => $this->getTable('catalog_product_entity')],
+                    'cp.entity_id = aw.' . static::COLUMN_PRODUCT_ID,
+                    []
+                )->joinInner(
+                    ['cpw' => $this->getTable('catalog_product_website')],
+                    'cpw.product_id = cp.entity_id',
+                    []
+                )->joinInner(
+                    ['cpsd' => $this->getTable('catalog_product_entity_int')],
+                    'cpsd.' . $linkField . ' = cp.' . $linkField . ' AND cpsd.store_id = 0' . ' AND cpsd.attribute_id = ' . $statusAttributeId, // Default store
+                    []
+                )->joinLeft(
+                    ['cpss' => $this->getTable('catalog_product_entity_int')],
+                    'cpss.' . $linkField . ' = cp.' . $linkField . ' AND cpss.attribute_id = cpsd.attribute_id' . ' AND cpss.store_id = ' . $store->getId(), // Store specific
+                    []
+                )->joinInner(
+                    ['cpvd' => $this->getTable('catalog_product_entity_int')],
+                    'cpvd.' . $linkField . ' = cp.' . $linkField . ' AND cpvd.store_id = 0' . ' AND cpvd.attribute_id = ' . $visibilityAttributeId, // Default store
+                    []
+                )->joinLeft(
+                    ['cpvs' => $this->getTable('catalog_product_entity_int')],
+                    'cpvs.' . $linkField . ' = cp.' . $linkField . ' AND cpvs.attribute_id = cpvd.attribute_id ' . ' AND cpvs.store_id = ' . $store->getId(), // Store specific
+                    []
+                )->joinLeft(
+                    ['cptn' => $this->getTable('catalog_product_entity_varchar')],
+                    'cptn.' . $linkField . ' = cp.' . $linkField . ' AND cptn.attribute_id = ' . $nameAttributeId . ' AND cptn.store_id = 0', // Default store
+                    []
+                )->joinLeft(
+                    ['cptns' => $this->getTable('catalog_product_entity_varchar')],
+                    'cptns.' . $linkField . ' = cp.' . $linkField . ' AND cptns.attribute_id = cptn.attribute_id AND cptns.store_id = ' . $store->getId(), // Store specific
+                    []
+                )->joinLeft(
+                    ['cpdp' => $this->getTable('catalog_product_entity_decimal')],
+                    'cpdp.' . $linkField . ' = cp.' . $linkField . ' AND cpdp.attribute_id = ' . $priceAttributeId . ' AND cpdp.store_id = 0', // Default store
+                    []
+                )->joinLeft(
+                    ['cpdps' => $this->getTable('catalog_product_entity_decimal')],
+                    'cpdps.' . $linkField . ' = cp.' . $linkField . ' AND cpdps.attribute_id = cpdp.attribute_id AND cpdps.store_id = ' . $store->getId(), // Store specific
+                    []
+                )->joinLeft(
+                    ['cpvu' => $this->getTable('catalog_product_entity_varchar')],
+                    'cpvu.' . $linkField . ' = cp.' . $linkField . ' AND cpvu.attribute_id = ' . $urlAttributeId . ' AND cpvu.store_id = 0', // Default store
+                    []
+                )->joinLeft(
+                    ['cpvus' => $this->getTable('catalog_product_entity_varchar')],
+                    'cpvus.' . $linkField . ' = cp.' . $linkField . ' AND cpvus.attribute_id = cpvu.attribute_id AND cpvus.store_id = ' . $store->getId(), // Store specific
+                    []
+                )->joinLeft(
+                    ['cpvi' => $this->getTable('catalog_product_entity_varchar')],
+                    'cpvi.' . $linkField . ' = cp.' . $linkField . ' AND cpvi.attribute_id = ' . $imgAttributeId . ' AND cpvi.store_id = 0', // Default store
+                    []
+                )->joinLeft(
+                    ['cpvis' => $this->getTable('catalog_product_entity_varchar')],
+                    'cpvis.' . $linkField . ' = cp.' . $linkField . ' AND cpvis.attribute_id = cpvi.attribute_id AND cpvis.store_id = ' . $store->getId(), // Store specific
+                    []
+                )->where(
+                    'cpw.website_id = ?',
+                    $store->getWebsiteId()
+                )->where(
+                    $this->connection->getIfNullSql('cpss.value', 'cpsd.value') . ' = ?',
+                    Status::STATUS_ENABLED
+                )->where(
+                    $this->connection->getIfNullSql('cpvs.value', 'cpvd.value') . ' IN (?)',
+                    [
+                        Visibility::VISIBILITY_IN_CATALOG,
+                        Visibility::VISIBILITY_IN_SEARCH,
+                        Visibility::VISIBILITY_BOTH
+                    ]
+                )->where(
+                    $this->connection->prepareSqlCondition(
+                        'aw.' . static::COLUMN_STORE_ID,
+                        ['in' => [0, $store->getId()]]
+                    )
+                )
+                ->group(
+                    'cp.entity_id'
+                )->columns(
+                    [
+                        ExampleInterface::ENTITY_COLUMN_SKU => 'cp.sku',
+                        ExampleInterface::ENTITY_COLUMN_BLOG_POST_ID => 'aw.' . $blogPostColumn,
+                        ExampleInterface::ENTITY_COLUMN_PRODUCT_ID => 'aw.' . static::COLUMN_PRODUCT_ID,
+                        ExampleInterface::ENTITY_COLUMN_STORE_ID => new Zend_Db_Expr(
+                            $this->connection->getIfNullSql('aw.' . static::COLUMN_STORE_ID, 0)
+                        ),
+                        ExampleInterface::ENTITY_COLUMN_NAME => new Zend_Db_Expr(
+                            $this->connection->getIfNullSql('cptns.value', 'cptn.value')
+                        ),
+                        ExampleInterface::ENTITY_COLUMN_PRICE => new Zend_Db_Expr(
+                            $this->connection->getIfNullSql('cpdps.value', 'cpdp.value')
+                        ),
+                        ExampleInterface::ENTITY_COLUMN_URL => new Zend_Db_Expr(
+                            $this->connection->getIfNullSql('cpvus.value', 'cpvu.value')
+                        ),
+                        ExampleInterface::ENTITY_COLUMN_IMAGE_URL => new Zend_Db_Expr(
+                            $this->connection->getIfNullSql('cpvis.value', 'cpvi.value')
+                        )
+                    ]
+                );
+
+            $this->productsSelects[$store->getId()] = $select;
+        }
+
+        return $this->productsSelects[$store->getId()];
+    }
+
+    /**
+     * Remove entry from index table once data has been reindexed
+     * @return int
+     */
+    protected function removeIndexEntry(int $storeId, int $postId, int $productId): int
+    {
+        $r = 1;
+        $t = $this->getIndexTable($storeId);
+        if ($t !== $this->resource->getMainTable()) {
+            $where = [
+                $this->connection->prepareSqlCondition(static::COLUMN_POST_ID, ['eq' => $postId]),
+                $this->connection->prepareSqlCondition(static::COLUMN_PRODUCT_ID, ['eq' => $productId]),
+                $this->connection->prepareSqlCondition(static::COLUMN_STORE_ID, ['eq' => $storeId])
+            ];
+            $r = (int)$this->connection->delete($this->getIndexTable($storeId), implode(' AND ', $where));
+        }
+        return $r;
+    }
+
+    /**
+     * @param ProductInterface $product
+     * @return string
+     */
+    protected function getProductImageFullUrl(ProductInterface $product): string
+    {
+        return $this->helper->getProductImageFullUrl($product);
+    }
+
+    /**
+     * @param Product $product
+     * @return float
+     */
+    protected function calculateProductPrice(ProductInterface $product): float
+    {
+        $price = (float) $product->getPrice();
+        switch ($product->getTypeId()) {
+            case Grouped::TYPE_CODE:
+
+                /** @var \Magento\GroupedProduct\Pricing\Price\FinalPrice  */
+                $priceInfo = $product->getPriceInfo()->getPrice('final_price');
+                $price = $priceInfo->getMinProduct()->getFinalPrice();
+            case Configurable::TYPE_CODE:
+
+                /** @var \Magento\ConfigurableProduct\Pricing\Price\ConfigurableRegularPrice */
+                $priceInfo = $product->getPriceInfo()->getPrice('regular_price');
+                $price = $priceInfo->getMinRegularAmount()->getValue();
+                break;
+            case Bundle::TYPE_CODE:
+
+                /** @var \Magento\Bundle\Pricing\Price\BundleRegularPrice */
+                $priceInfo = $product->getPriceInfo()->getPrice('final_price');
+                $price = $priceInfo->getMinimalPrice()->getValue();
+                break;
+            default:
+                return (float) $product->getFinalPrice();
+        }
+        return $price;
+    }
+}
+```
+
+![Magento Exam Information](./images/icon-info.png)TODO
+
+*   Table Maintainers
+*   Temporary Tables
+*   Flat Tables
+
+![Magento Exam Question](./images/icon-question.png)**Describe the Materialized View pattern?**
+
+> **MView** stands for **Materialized View** which is a snapshot of the database at a point in time.
+>
+> **Materialized View (mview)** Allows tracking database changes for a certain entity (product, category and so on) and running change handler.
+>
+> Mview emulates the materialized view technology for **MySQL using triggers** and separate materialization process (provides executing PHP code instead of SQL queries, which allows materializing multiple queries).`Indexers are costly to run, especially when there is traffic on category pages, customers place orders whilst admins save products etc.
+>
+> *Example:*
+> On product save the cache gets invalidated (off topic). In case of stock indexer, before it ends the execution, it sends the entity ids affected as cache tags to be cleaned (full page cache type).
+>
+> Product **creates a changelog** in the change handler which creates a backlog in indexers such as catalog_category_product, catalog_product_category, catalog_product_attribute, catalog_product_price etc. This informs the indexers that updates to the [EAV](#h.915l1avejvsh) need to be made for specific products.
+>
+> The state of the mview can be seen in the mview_state database table which holds different current versions of each indexer.
+
+![Magento Exam Question](./images/icon-question.png)**What is the difference between Index On Save and Index On Schedule?**
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Update On Save
+
+> Indexers are run immediately after entities are saved. E.g. when a product is saved in the admin. This sounds fine but...
+> When you save a product Magento recalculates every single product on the storefront. Worse still, refreshing the index will clear the Full Page Cache (FPC) which affects all pages.
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Update On Schedule
+
+> Indexers are run via a scheduled task (CRON) which by default runs every minute. When a product is saved in the admin it will run the indexing in the background. It aims to remedy the problems with Update On Save by jsut indexing the data that has changed
+
+![Magento Exam Information](./images/icon-info.png)You should almost always have indexers set to Update On Schedule if you don't wish to affect FPC and therefore your site's performance.
\ No newline at end of file
diff --git a/2. Request Flow Processing/1. Utilize modes and application initialization.md b/2. Request Flow Processing/1. Utilize modes and application initialization.md
deleted file mode 100644
index 4875813..0000000
--- a/2. Request Flow Processing/1. Utilize modes and application initialization.md	
+++ /dev/null
@@ -1,157 +0,0 @@
-# Utilize modes and application initialization
-
-## Identify the steps for application initialization.
-[app/bootstrap.php](https://github.com/magento/magento2/blob/2.3/app/bootstrap.php):
-
-- composer autoloader, functions, umask, timezone UTC, php precision
-
-[\Magento\Framework\App\Bootstrap](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/App/Bootstrap.php)::*create*
-
-- configure autoloader - PSR-4 prepend generation\Magento
-
-[\Magento\Framework\App\Bootstrap](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/App/Bootstrap.php)::*createApplication*
-
-- just call object manager->create
-
-[\Magento\Framework\App\Bootstrap](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/App/Bootstrap.php)::*run*
-
-- set error handler
-- assert maintenance
-- assert installed
-- response = application->*launch*()
-- response->*sendResponse*()
-- on error: application->catchException
-- on missed error:
-  - dev mode: print exception trace
-  - normal mode: log, message "An error has happened during application run. See exception log for details."
-
-### Application class
-
-[bootstrap->createApplication()](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/App/Bootstrap.php#L230) 
-
-  - [\Magento\Framework\App\Http](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/App/Http.php) - index.php, pub/index.php
-    load config area by front name
-    front controller->dispatch
-    event `controller_front_send_response_before`
-
-  - [\Magento\Framework\App\Cron](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/App/Cron.php) - pub/cron.php
-    config area `crontab`
-    load translations
-    dispatch event `default`
-
-  - [\Magento\MediaStorage\App\Media](https://github.com/magento/magento2/blob/2.3/app/code/Magento/MediaStorage/App/Media.php) - pub/get.php
-    access /media/* when using DB image storage and physical file doesn't exist
-
-  - [\Magento\Framework\App\StaticResource](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/App/StaticResource.php) - pub/static.php
-    404 in production
-    /$area/$resource/$file/... params, load config by params
-    sends file in response
-    assetRepo->createAsset - \Magento\Framework\View\Asset\File
-    assetPublisher->publish - materialize (copy/symlink) file if doesn't exist
-
-  - [\Magento\Indexer\App\Indexer](https://github.com/magento/magento2/blob/2.3/app/code/Magento/Indexer/App/Indexer.php) - module-indexer, unused?
-  - [\Magento\Backend\App\UserConfig](https://github.com/magento/magento2/blob/2.3/app/code/Magento/Backend/App/UserConfig.php) - module-backend, unused?
-
-Notes:
-
-- Responsibility - launch() and return response
-- Roughly different application class matches different physical file entry points (index.php, media.php, get.php, static.php, cron.php)
-- Front controller exists only in Http application
-- There's no CLI application, Symfony command is used
-
-### HTTP application
-
-[\Magento\Framework\App\Http::launch](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/App/Http.php#L128)
-1. detect config area by front name
-
-```php
-<?php
-$areaCode = $this->_areaList->getCodeByFrontName($this->_request->getFrontName());
-$this->_state->setAreaCode($areaCode);
-$this->_objectManager->configure($this->_configLoader->load($areaCode));
-```
-
-`\Magento\Framework\App\AreaList` - areas from argument di.xml ([AreaList](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/App/AreaList.php))
-
-- frontend = [frontname null, router "standard"] --- *default when nothing matched*
-- adminhtml - [frontNameResolver=..., router "admin"]
-  [\Magento\Backend\App\Area\FrontNameResolver::getFrontName(checkhost)](https://github.com/magento/magento2/blob/2.3/app/code/Magento/Backend/App/Area/FrontNameResolver.php#L83)
-  system config `admin/url/use_custom`, `admin/url/custom`
-- crontab = null
-- webapi_rest = [frontName `/rest`]
-- webapi_soap = [frontname `/soap`]
-
-1. [ObjectManagerInterface->configure()](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/ObjectManager/ObjectManager.php#L82) - selected area code
-1. result = FrontControllerInterface->dispatch()
-1. [ResultInterface->renderResult()](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Controller/AbstractResult.php#L122) into response object
-1. event `controller_front_send_response_before` (request, response)
-
-
-### How would you design a customization that should act on every request and capture output data regardless of the controller?
-- event `controller_front_send_response_before`
-
-
-## Describe front controller responsibilities
-
-*Front controller* exists only in Http application (pub/index.php)
-
-- Same entry point, how to execute different logic?
-  Via different DI preference depending on detected config area (areaList->getCodeByFrontName)
-- *Default* global preference app/etc/di.xml - Magento\Framework\App\FrontController
-- "frontend", "adminhtml", "crontab" area code - no preference, use default *App\FrontController*
-- "webapi_rest (frontName `/rest`) - preference module-webapi/etc/webapi_rest/di.xml - *\Magento\Webapi\Controller\Rest*
-- "webapi_soap" (frontname `/soap`) - preference module-webapi/etc/webapi_soap/di.xml - *\Magento\Webapi\Controller\Soap*
-
-### [\Magento\Framework\App\FrontController](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/App/FrontController.php):
-
-- routerList
-- action = router[].match
-- result = action.dispatch() or action.execute()
-- noroute action fallback
-
-### Router match - action can be:
-
-- generic \Magento\Framework\App\ActionInterface::execute - not used?
-- [\Magento\Framework\App\Action\AbstractAction](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/App/Action/AbstractAction.php)::dispatch - context, request, response, result factory, result redirect factory
-
-### Dispatch/execute action - result can be:
-
-- [\Magento\Framework\Controller\ResultInterface](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Controller/ResultInterface.php) - renderResult, setHttpResponseCode, setHeader
-
-    Implementations:
-    - [Result\Raw](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Controller/Result/Raw.php) -> Result\AbstractResult
-    - [Result\Json](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Controller/Result/Json.php) -> Result\AbstractResult
-    - [Result\Forward](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Controller/Result/Forward.php) -> Result\AbstractResult
-    - [\Magento\Framework\View\Result\Layout](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/View/Result/Layout.php) -> Result\AbstractResult
-    - [\Magento\Framework\View\Result\Page](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/View/Result/Page.php) -> \Magento\Framework\View\Result\Layout
-    - [Result\Redirect](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Controller/Result/Redirect.php) -> Result\AbstractResult
-
-- [\Magento\Framework\App\ResponseInterface](https://github.com/magento/magento2/blob/2.3/lib/internal//Magento/Framework/App/ResponseInterface.php) - sendResponse
-
-    Implementations:
-    - [Console\Response](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/App/Console/Response.php)
-    - [\Magento\MediaStorage\Model\File\Storage\FileInterface](https://github.com/magento/magento2/blob/2.3/app/code/Magento/MediaStorage/Model/File/Storage/Response.php) -> \Magento\Framework\App\Response\Http
-    - [\Magento\Framework\HTTP\PhpEnvironment\Response](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/HTTP/PhpEnvironment/Response.php) -> \Zend\Http\PhpEnvironment\Response
-    - [\Magento\Framework\Webapi\Response](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Webapi/Response.php) -> \Magento\Framework\HTTP\PhpEnvironment\Response
-    - [\Magento\Framework\Webapi\Rest\Response](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Webapi/Rest/Response.php) -> \Magento\Framework\Webapi\Response
-
-### [\Magento\Webapi\Controller\Rest](https://github.com/magento/magento2/blob/2.3/app/code/Magento/Webapi/Controller/Rest.php) -> \Magento\Framework\App\FrontControllerInterface:
-
-- preference for FrontController set in [etc/webapi_rest/di.xml](https://github.com/magento/magento2/blob/2.3/app/code/Magento/Webapi/etc/webapi_rest/di.xml#L32)
-- process path [/$store]/... - specific store, [/all]/... - admin store (0), /... - default store
-- a. process schema request /schema
-- b. or process api request (resolve route, invoke route -> service class with params)
-
-### [\Magento\Webapi\Controller\Soap](https://github.com/magento/magento2/blob/2.3/app/code/Magento/Webapi/Controller/Soap.php) -> \Magento\Framework\App\FrontControllerInterface:
-
-- process path (same as REST)
-- a. generate WSDL ?wsdl
-- b. or generate WSDL service list ?wsdl_list
-- c. or handle SOAP (native PHP)
-
-
-### In which situations will the front controller be involved in execution, and how can it be used in the scope of customizations?
-
-- Front controller is only used in HTTP application - pub/index.php
-- involved in `frontend` and `adminhtml` (HTTP\App\FrontController), `webapi_rest` (Controller\Rest), `webapi_soap` (Controller\Soap) areas
-- HTTP customization - register router and place custom code in match() method
diff --git a/2. Request Flow Processing/2. Demonstrate ability to process URLs in Magento.md b/2. Request Flow Processing/2. Demonstrate ability to process URLs in Magento.md
deleted file mode 100644
index fc642cf..0000000
--- a/2. Request Flow Processing/2. Demonstrate ability to process URLs in Magento.md	
+++ /dev/null
@@ -1,187 +0,0 @@
-# Demonstrate ability to process URLs in Magento
-## Describe how Magento processes a given URL.
-
-urlBuilder - [\Magento\Framework\UrlInterface](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/UrlInterface.php): getUrl
-
-Instances:
-
-- [\Magento\Framework\Url](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Url.php)
-- [\Magento\Backend\Model\Url](https://github.com/magento/magento2/blob/2.3/app/code/Magento/Backend/Model/Url.php)
-
-1. preprocess route params
-
-    \Magento\Framework\Url\*RouteParamsPreprocessorInterface*::execute
-    - composite - delegates to many instances
-    - staging - Preview\RouteParamsPreprocessor
-      * if frontend and preview, adds `?___version`
-      * if store code in URL, adds `?___store`
-
-1. Disable caching if object found in route params
-1. *createUrl* (may be cached in memory)
-
-    - stash all parameters `_fragment`, `_escape`, `_escape_params`, `_query`, `_nosid`
-    - \Magento\Framework\Url::*getRouteUrl* - without any system params
-    - then compile ?query and #fragment params
-
-1. run modifier
-
-    \Magento\Framework\Url\ModifierInterface::execute - mode entire/base
-    - composite - delegates to many instances
-    - staging - Url\BaseUrlModifier - only base mode
-      In frontend and preview, replaces host part with `$_SERVER[HTTP_HOST]`
-
-*getRouterUrl*:
-
-- `_direct` option = baseUrl + `_direct`
-- $routeName/$controllerName/$actionName/$param1/$value1/...
-
-### How do you identify which module and controller corresponds to a given URL?
-
-- first part is route name. Search routes.xml for route with matching *ID*
-- modules for this ID are sorted with "before" and "after"
-- controller/action classes is searched in matched modules
-
-### What is necessary to create a custom URL structure?
-
-- register custom router, e.g. [Magento\Robots\Controller\Router](https://github.com/magento/magento2/blob/2.3/app/code/Magento/Robots/Controller/Router.php)
-- create rewrite record for specific URL
-
-
-## Describe the URL rewrite process and its role in creating user-friendly URLs.
-
-Router `urlrewrite `:
-- `?____from_store` param, redirect to new URL if necessary.
-
-  Example:
-  - on English store category page /shoes switching to Norwegian store
-  - _/no/shoes?____from_store=1_
-  - find new rewrite for norwegian store
-  - 302 redirect to _/no/sko_
-
-- find rewrite by request path
-- redirect if necessary
-- return forward action - mark request not dispatched, force continue router loop
-
-
-### How is getUrl('catalog/product/view/id/1') replaced with rewrite?
-
-- Product->getProductUrl
-- Product\Url->getProductUrl
-- Product\Url->getUrl
-- UrlFinderInterface->findOneByData
-- new Url->getUrl -- `_direct` if rewrite found = baseUrl . requestPath
-
-Rewrite is not used with regular getUrl, only when module uses explicitly (catalog, CMS).
-
-### CMS URL rewrite
-
-- On event `cms_page_save_after`, if identifier or store changed, deletes and creates new rewrites.
-- Doesn't create redirect rewrite for renamed redirects.
-- CMS page opens with UrlRewrite router (priority 20), not CMS router (priority 60).
-
-### How are user-friendly URLs established, and how are they customized?
-
-Module UrlRewrite:
-- \Magento\UrlRewrite\Model\UrlPersistInterface::deleteByData
-- \Magento\UrlRewrite\Model\UrlPersistInterface::replace
-
-Product:
-
-- event `catalog_product_save_before` - generate URL key by product name (if url key wasn't provided)
-  * [ProductUrlKeyAutogeneratorObserver](https://github.com/magento/magento2/blob/2.3/app/code/Magento/CatalogUrlRewrite/Observer/ProductUrlKeyAutogeneratorObserver.php)
-  * [\Magento\CatalogUrlRewrite\Model\ProductUrlPathGenerator::getUrlKey](https://github.com/magento/magento2/blob/2.3/app/code/Magento/CatalogUrlRewrite/Model/ProductUrlPathGenerator.php#L125)
-  
-- event `catalog_product_save_after` - generate and replace URL rewrites (when changed url_key, categories, websites or visibility)
-  * [ProductProcessUrlRewriteSavingObserver](https://github.com/magento/magento2/blob/2.3/app/code/Magento/CatalogUrlRewrite/Observer/ProductProcessUrlRewriteSavingObserver.php)
-  * [\Magento\CatalogUrlRewrite\Model\ProductUrlRewriteGenerator::generate](https://github.com/magento/magento2/blob/2.3/app/code/Magento/CatalogUrlRewrite/Model/ProductUrlRewriteGenerator.php#L128)
-  * deleteByData, replace
-
-Category:
-
-- event `catalog_category_save_before` - generate URL key, update child categories
-  * [CategoryUrlPathAutogeneratorObserver](https://github.com/magento/magento2/blob/2.3/app/code/Magento/CatalogUrlRewrite/Observer/CategoryUrlPathAutogeneratorObserver.php)
-  * \Magento\CatalogUrlRewrite\Observer\CategoryUrlPathAutogeneratorObserver::updateUrlPathForChildren
-  * \Magento\CatalogUrlRewrite\Observer\CategoryUrlPathAutogeneratorObserver::updateUrlPathForCategory
-  * \Magento\CatalogUrlRewrite\Model\CategoryUrlPathGenerator::getUrlPath
-  * child category.url_path
-
-- event `catalog_category_save_after` - when changed (key, anchor, products)
-  * [CategoryProcessUrlRewriteSavingObserver](https://github.com/magento/magento2/blob/2.3/app/code/Magento/CatalogUrlRewrite/Observer/CategoryProcessUrlRewriteSavingObserver.php#L90)
-  * [\Magento\CatalogUrlRewrite\Observer\UrlRewriteHandler::generateProductUrlRewrites](https://github.com/magento/magento2/blob/2.3/app/code//Magento/CatalogUrlRewrite/Observer/UrlRewriteHandler.php#L124)
-  * ... lots of logic
-
-
-## Describe how action controllers and results function.
-
-[App\Action\Action::dispatch](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/App/Action/Action.php#L91):
-
-- event `controller_action_predispatch`
-- event `controller_action_predispatch_$routeName`, e.g. `..._checkout`
-- event `controller_action_predispatch_$fullActionName`, e.g. `..._checkout_cart_index`
-- stop if FLAG_NO_DISPATCH
-- *execute* - all action controllers implement this
-- stop if FLAG_NO_POST_DISPATCH
-- event `controller_action_postdispatch_$fullActionName`
-- event `controller_action_postdispatch_$routeName`
-- event `controller_action_postdispatch`
-- if action doesn't return result, response object is returned -- action can just modify response object
-
-
-### How do controllers interact with another?
-
-- Controller\Response\Forward - changes request params, marks request not dispatched, so front controller
-  will match again and new controller will be executed
-- Controller\Response\Redirect - another controller URL
-
-### How are different response types generated?
-[\Magento\Framework\Controller\ResultInterface](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Controller/ResultInterface.php):
-- renderResult
-- setHttpResponseCode
-- setHeader
-
-[Controller\AbstractResult](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Controller/AbstractResult.php):
-
-- *renderResult* - required by interface - applies headers and calls *render*. children must implement this
-- setHttpResponseCode
-- setHeader
-- setStatusHeader
-
-[Controller\Result\Raw](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Controller/Result/Raw.php):
-
-- setContents
-- *render* - set response body
-
-[Controller\Result\Json](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Controller/Result/Json.php):
-
-- setData - array
-- setJsonData - string
-- *render* - processes inline translations, sets application/json header and response body json string
-
-[Controller\Result\Forward](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Controller/Result/Forward.php):
-
-- setModule, setController, setParams
-- *forward* - does the trick, modifies request object, marks request not dispatched
-- *render* - does nothing, forward must be called manually
-
-[Controller\Result\Redirect](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Controller/Result/Redirect.php):
-
-- setUrl, setPath - custom address
-- setRefererUrl, setRefererOrBaseUrl - go back function
-
-[View\Result\Layout](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/View/Result/Layout.php): - renders layout without `default` handle and page layout (1-column etc.)
-
-- *renderResult*
-  * event `layout_render_before`
-  * event `layout_render_before_$fullActionName`, e.g. `..._checkout_cart_index`
-  * render
-
-- *render* - layout->getOutput, translate inline, set response body
-- addDefaultHandle = $fullActionName, e.g. `checkout_cart_index`
-- addHandle, addUpdate
-
-[View\Result\Page](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/View/Result/Page.php): - wraps layout into page layout
-- same events as above
-- *render* - renders layout, assigns vars and renders outer page template
-- assign - values into viewVars property. default
-  Default: requireJs, headContent, headAdditional, htmlAttributes, headAttributes, bodyAttributes, loaderIcon, layoutContent
-- addDefaultHandle = $fullActionName + `default`
diff --git a/2. Request Flow Processing/3. Demonstrate ability to customize request routing.md b/2. Request Flow Processing/3. Demonstrate ability to customize request routing.md
deleted file mode 100644
index 0a36f95..0000000
--- a/2. Request Flow Processing/3. Demonstrate ability to customize request routing.md	
+++ /dev/null
@@ -1,57 +0,0 @@
-# 2.3 Demonstrate ability to customize request routing
-
-## Describe request routing and flow in Magento.
-
-[Frontend routers](https://devdocs.magento.com/guides/v2.2/extension-dev-guide/routing.html):
-
-- robots (10)
-- urlrewrite (20)
-- standard (30) - module/controller/action
-  * get modules by front name registered in routes.xml
-  * find action class
-  * if action not found in all modules, searches "noroute" action in *last* module
-
-- cms (60)
-- default (100) - noRouteActionList - 'default' noroute handler
-
-Adminhtml routers:
-
-- admin (10) - extends base router - module/controller/action, controller path prefix "adminhtml"
-- default (100) - noRouteActionList - 'backend' noroute handler
-
-Default router (frontend and backend):
-
-- noRouteHandlerList. process
-  + backend (10)
-    *Default admin 404 page* "adminhtml/noroute/index" when requested path starts with admin route.
-
-  + default (100)
-    *Default frontend 404 page* "cms/noroute/index" - admin config option `web/default/no_route`.
-
-- always returns forward action - just mark request not dispatched - this will continue match loop
-
-
-### When is it necessary to create a new router or to customize existing routers?
-
-Create new router when URL structure doesn't fit into module/controller/action template,
-e.g. fixed robots.txt or dynamic arbitraty rewrites from DB.
-
-If you want to replace controller action, you can register custom module in controller lookup sequence -
-reference route by ID and add own module "before" original module.
-
-### How do you handle custom 404 pages?
-
-1. If [front controller](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/App/FrontController.php#L61-L65) catches [\Magento\Framework\Exception\NotFoundException](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/Exception/NotFoundException.php), it changes action name *"noroute"* and continues loop.
-   E.g. catalog/product/view/id/1 throws NotFoundException. catalog/product/noroute is checked.
-
-1. If standard router recognizes front name but can't find controller, it tries to find *"noroute"*
-   action from last checked module.
-   E.g. catalog/brand/info controller doesn't exist, so catalog/brand/noroute will be checked.
-   
-   [\Magento\Framework\App\Router\Base::getNotFoundAction](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/App/Router/Base.php#L237)
-
-1. If all routers didn't match, default controller provides two opportunities:
-  - set default 404 route in admin config `web/default/no_route` (see: [\Magento\Framework\App\Router\NoRouteHandler::process](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/App/Router/NoRouteHandler.php#L34))
-  - register custom handler in [noRouteHandlerList](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/App/Router/NoRouteHandlerList.php):
-    * backend (sortOrder: 10) [Magento\Backend\App\Router\NoRouteHandler](https://github.com/magento/magento2/blob/2.3/app/code/Magento/Backend/App/Router/NoRouteHandler.php#L44) -> `adminhtml/noroute/index`
-    * default (sortOrder: 100) [Magento\Framework\App\Router\NoRouteHandler](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/App/Router/NoRouteHandler.php)
diff --git a/2. Request Flow Processing/4. Determine the layout initialization process.md b/2. Request Flow Processing/4. Determine the layout initialization process.md
deleted file mode 100644
index 6223c03..0000000
--- a/2. Request Flow Processing/4. Determine the layout initialization process.md	
+++ /dev/null
@@ -1,369 +0,0 @@
-# Determine the layout initialization process
-
-## Determine how layout is compiled.
-
-View\Layout::*build* = View\Layout\Builder::*build* - once
-
-1. loadLayoutUpdates - reads layout xml files and DB updates by *current handles*, result in `_updates` array
-
-    * event `layout_load_before`
-
-1. generateLayoutXml - joins `_updates` into XML string, loads XML object, initiailzes `_elements` = []
-
-    * layout.generateXml
-    * no events
-
-1. generateLayoutBlocks - layout.generateElements
-
-    * event `layout_generate_blocks_before`
-    * readerPool->interpret - every reader checks for matching xml node name (attribute, body, head etc.), prepares page structure 
-    * generatorPool->process
-    * add top-level element as outputElement. default "root"
-    * event `layout_generate_blocks_after`
-
-```
-builder.generateLayoutBlocks -> layout.generateElements
-readerPool.*interpret* -- schedules
-  nodeReaders[type].interpret each element -- Layout\ReaderInterface
-  - html, move
-  - body - own readerPool.interpret, but without 'body' reader
-  - head - css,script,link,remove,meta,title,attribute
-  - 'container', 'referenceContainer' --> Layout\Reader\Container
-  - 'block', 'referenceBlock' --> Layout\Reader\Block
-  - uiComponent
-  View\Layout\ReaderInterface::interpret -- html, body, head, ui component, reader pool, container, move, block
-
-View\Layout\GeneratorPool.process -- generates blocks
-  buildStructure
-  generator[].*process*
-  - head, body
-  - block - creates blocks, sets layout, event `core_layout_block_create_after`, block 'actions'
-  - container - sets tag, id, class, label, display
-  - uiComponent - creates wrapper element, prepareComponent recursively etc.
-
-getOutput
-- renderElement(root)
-  - renderNonCachedElement(root) -- hardcoded switch
-    - is uiComponent -> toHtml
-    - is block -> toHtml
-    - is container -> renderElement(child[])
-  - event `core_layout_render_element`
-```
-
-### How would you debug your layout.xml files and verify that the right layout instructions are used?
-
-When XML object is created from string XML updates, this is a good place to examine resuls.
-View\Layout\Builder.generateLayoutXml or View\Layout.generateXml is a good place to dump structure.
-
-## Determine how HTML output is rendered.
-
-First external code calls layout.addOutputElement(name) to register top level elements for output generation.
-When layout.*getOutput* is called, it renders each outputElement.
-
-- View\Layout::getOutput
-- for every registered `_output` element
-- View\Layout::renderElement
-
-When layout is build initially, it finds top level container and registers it as addOutputElement - default "root".
-
-### How does Magento flush output, and what mechanisms exist to access and customize output?
-
-Render response:
-
-- action controller returns ResponseInterface object, e.g. View\Response\Page
-- front controller returns this response
-- App\Http.launch application renders result, calling response.renderResult
-- controller response renders contents and assigns to response.body
-- App\Http event `controller_front_send_response_before` allows to modify response before returning
-- App\Bootstrap object gets response object from App\Http
-- response.sendResponse - Zend implementation - send headers, send content
-
-Customize:
-
-1. modify any response in event `controller_front_send_response_before`
-1. View\Element\AbstractBlock::toHtml event `view_block_abstract_to_html_after`
-
-## Determine module layout XML schema.
-
-Module layouts:
-
-- module/view/base/layout/
-- module/view/frontend/layout/
-- module/view/adminhtml/layout/
-
-### layout_generic.xsd
-
-Generic layout - useful for returning Ajax response. Doesn't have body, head, css etc., only pure structure:
-
-```xml
-<layout xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-  xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/layout_generic.xsd">
-  <container
-    name="" as="" after="" before="" label=""
-    output=""
-    htmlTag="" htmlClass="" htmlId=""
-  />
-  <referenceContainer
-    name="" label=""
-    htmlTag="" htmlClass="" htmlId=""
-    display="true/false"
-    remove="true/false"
-  />
-  <block
-    class="" name="" as="" template="" before="" after="" group=""
-    acl="" aclResource="" ifconfig=""
-    output="" cacheable="bool" ttl="int"
-  />
-  <referenceBlock name="" template="" display="" remove="" />
-  <update handle="name" />
-  <move element="" destination="" as="" after="" before="" />
-  <uiComponent
-    component="" name="" as="" before="" after="" group=""
-    aclResource="" ifconfig=""
-    output="" cacheable="" ttl=""
-  />
-</config>
-```
-
-### page_configuration.xsd
-
-Same as layout plus:
-
-- top level layout selection
-- structure is wrapped in body node
-- additional nodes - html attribute, head title, attribute and scripts
-
-```xml
-<page
-  layout="1column"
-  label=""
-  design_abstraction="custom / page_layout"
-
-  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-  xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd"
->
-  <html>
-    <attribute name="" value="" />
-  </html>
-  <head>
-    <title>Title</title>
-    <css src defer ie_condition charset hreflang media rel rev sizes target type src_type />
-    <link src defer ie_condition charset hreflang media rel rev sizes target type src_type />
-    <meta content charset http-equiv name scheme />
-    <script src defer ie_condition async charset type src_type />
-    <remove src="" />
-    <attribute name="" value="" />
-  </head>
-  <update handle="" />
-  <body>
-    <attribute name="" value="" />
-    <!-- container/block structure same as in generic layout -->
-  </body>
-</page>
-```
-
-### layouts.xml - declare available page layouts
-
-- <module_dir>/view/<area>/layouts.xml
-- <theme_dir>/<Namespace>_<Module>/layouts.xml
-
-- base:
-  * empty
-
-- frontend:
-  * 1column - extends empty
-  * 2columns-left - extends 1column
-  * 2columns-right - same as 2columns-left
-  * 3columns - same as 2columns-left
-
-- adminhtml:
-  * admin-empty
-  * admin-1column
-  * admin-2columns-left
-
-### page_layout.xsd
-
-Only containers
-
-```xml
-<layout xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-  xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_layout.xsd">
-  <referenceContainer />
-  <container />
-  <update />
-  <move />
-</layout>
-```
-
-### layout result.renderResult:
-
-- layout.getOutput
-- layout.build
-- View\Layout\Builder.build:
-
-    * loadLayoutUpdates
-    * generateLayoutXml
-    * generateLayoutBlocks
-
-
-- create result page - adds default handles
-- page builder.build
-- all normal layout XML is collected and is about to create blocks
-- custom step before generating layout blocks
-
-
-### page result.renderResult:
-- View\Result\PageFactory.create
-- View\Result\Page::addDefaultHandle - `default`, `$fullActionName`
-
-- View\Page\Config.publicBuild = build
-- View\Page\Builder.build - extends View\Layout\Builder, custom readPageLayout on step generateLayoutBlocks
-
-    * (inherit) loadLayoutUpdates
-    * (inherit) generateLayoutXml
-    * generateLayoutBlocks - additionally *readPageLayout*
-
-        + right before creating actual blocks, reads and merges page layout xml files
-        + new instance of View\Model\Layout\Merge::load handles = '1column' -- uses subDir 'page_layout'
-        + *interprets* found page nodes - schedules blocks. page layout instructions (root page template) are interpreted before others
-        + original generateLayoutBlocks *interprets*, then runs *generators*
-
-- check View\Page\Config.pageLayout, e.g. "1column"
-- adds default body classes - `$fullActionName`, `page-layout-$layout`
-- renders block 'head.additional', 'require.js'
-- assigns vars 'requireJs', 'headContent', 'headAdditional', 'htmlAttributes', 'headAttributes', 'bodyAttributes', 'loaderIcon'
-- layout.getOutput -- already built
-- renderPage
-
-    * result.template defined via app/etc/di.xml
-    * include Magento_Theme::root.phtml
-
-
-### In your custom controller don't forget to add entity-specific IDs:
-
-$page->addPageLayoutHandles(['id' => $category->getId()]);
-
-- adds handle `$fullActionName_$param_$value` like `catalog_category_view_id_17`
-- informs full page cache of *entity specific page* \Magento\Framework\View\EntitySpecificHandlesList::addHandle
-
-    * \Magento\PageCache\Model\Layout\MergePlugin::beforeValidateUpdate - entity-specific layout handles must not contain TTL
-
-        e.g. catalog_category_view_id_15.xml: <block ttl="3600"> ... will throw error
-
-    * \Magento\PageCache\Observer\ProcessLayoutRenderElement::_wrapEsi - exclude entity-specific handles from ESI URL
-
-
-
-View\Layout\Builder.build
-
-- loadLayoutUpdates
-- generateLayoutXml
-- generateLayoutBlocks
-
-View\Page\Builder.build
-
-- extend generateLayoutBlocks
-- readPageLayout
-
-### File Collector
-
-- View\File\CollectorInterface
-- View\File\Collector\Decorator\ModuleDependency - Decorator that sorts view files according to dependencies between modules they belong to
-- View\File\Collector\Decorator\ModuleOutput - Decorator that filters out view files that belong to modules, output of which is prohibited
-- View\File\Collector\Base - Source of base files introduced by modules
-
-Collector\Base - Source of base files introduced by modules
-
-- view/base/, view/{$area}/
-
-Collector\Override\Base - Source of view files that explicitly override base files introduced by modules
-
-- theme/{$namespace}_{$module}/
-
-Collector\Theme - Source of view files introduced by a theme
-
-- theme/
-
-Collector\Override\ThemeModular - Source of view files that explicitly override modular files of ancestor themes
-
-- theme/{$namespace}_{$module}/{$themeVendor}/{$themeName}/
-
-Collector\Library - Source of base layout files introduced by modules
-
-- lib_web/
-- each inherited theme[]: theme/web/
-
-### How do you add new elements to the pages introduced by a given module?
-
-```
-<block class="module\block\class" template="new module template" ... />
-```
-
-## Demonstrate the ability to use layout fallback for customizations and debugging.
-
-- View\Element\Template::getTemplateFile
-- View\Element\Template\File\Resolver::getTemplateFileName(template, [module, area]) -- just caches in memory
-- View\FileSystem::getTemplateFileName -- detects module by Module_Name::template.phtml, adds default params
-  * View\Asset\Repository::updateDesignParams - adds default missing params [object themeModel, locale]
-
-- View\Design\FileResolution\Fallback\TemplateFile.getFile(area, ) -- minify html
-- View\Design\FileResolution\Fallback\File.getFile -- calls resolver type='file'
-- View\Design\FileResolution\Fallback\Resolver\Simple.resolve
-- View\Design\Fallback\RulePool.getRule - by type: file, locale file, template file
-
-  *File fallback rule*:
-  - when missing 'module_name':
-    * <theme_dir>
-  - when set 'module_name':
-    * <theme_dir>/<module_name>/templates
-    * <module_dir>/view/<area>/templates
-    * <module_dir>/view/base/templates
-
-- View\Design\FileResolution\Fallback\Resolver\Simple::resolveFile(fileRule)
-- search file in each directory
-
-### How do you identify which exact layout.xml file is processed in a given scope?
-
-
-## How does Magento treat layout XML files with the same names in different modules?
-
-They are merged in module sequence order. Additionally, modules marked as "disable module output"
-are skipped (though deprecated).
-
-View\File\Collector\Decorator\ModuleDependency - Decorator that sorts
-view files according to dependencies between modules they belong to
-
-View\File\Collector\Decorator\ModuleOutput - Decorator that filters out
-view files that belong to modules, output of which is prohibited
-
-View\File\Collector\Base - Source of base files introduced by modules
-
-## Identify the differences between admin and frontend scopes.
-
-- customized layout builder and page builders - automatically init messages block
-- custom parent \Magento\Backend\Block\AbstractBlock
-  * auto inject AuthorizationInterface
-
-- custom parent \Magento\Backend\Block\Template:
-  * available some properties - authorization, mathRandom, backendSession, formKey, class nameBuilder
-  * event `adminhtml_block_html_before` - fired only when non-cached render.
-    To compare, event `view_block_abstract_to_html_after` fires even when block loaded from cache
-
-- customized "block" layout reader (runs interpret) -- reads "acl" block attribute
-- customzied "block" layout generator - default block "class=Magento\Backend\Block\Template"
-- controller result object with additional methods:
-  * setActiveMenu
-  * addBreadcrumb
-  * addContent(block) - moves to 'content'
-  * addLeft(block)
-  * addJs
-  * moveBlockToContainer
-
-### What differences exist for layout initialization for the admin scope?
-
-*Custom layout and page builders* - automatically initializes message block from message manager:
-\Magento\Backend\Model\View\Layout\Builder and \Magento\Backend\Model\View\Page\Builder:
-- afterGenerateBlock - called in the end of generateLayoutBlocks, the end of generation - `layout->initMessages()`
-- getBlock('messages') or create new one
-- addMessages from Message\ManagerInterface
-- addStorageType('default')
diff --git a/2.Magento-Request-Flow-Processing.md b/2.Magento-Request-Flow-Processing.md
new file mode 100755
index 0000000..0062e45
--- /dev/null
+++ b/2.Magento-Request-Flow-Processing.md
@@ -0,0 +1,669 @@
+2 - Request Flow Processing
+============================
+
+2.0 Identify the steps for application initialization.
+------------------------------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**What is [app/bootstrap.php](https://github.com/magento/magento2/blob/2.2-develop/app/bootstrap.php&sa=D&ust=1609223264555000&usg=AOvVaw0Srn64dGW6XbRge8k-JR_B) used for?**
+
+> Production Mode: `pub/index.php` (entry point) in the site root or in pub/index.php.
+> Developer mode: `index.php` (entry point in the website root).
+> To run the Magento application, the following actions are implemented in `index.php`:
+
+*   Include `app/bootstrap.php` which performs essential initialization routines, such as:
+*   Initializing the error handler.
+*   Initializing the autoloader.
+*   Creates the Object Manager and basic shared services that are used everywhere and are affected by the environment. The environment parameters are injected properly into these objects.
+*   Asserts that maintenance mode is not enabled; otherwise, terminates.
+*   Asserts that the Magento application is installed; otherwise, terminates.
+*   Setting profiling options
+*   Setting the default timezone (UTC).
+*   Create an instance of `Magento\Framework\App\Bootstrap`.
+*   Create a Magento application instance (`Magento\Framework\AppInterface`).
+*   Starts the Magento application
+
+*   Any uncaught exception during application launch is automatically passed back to Magento in the catchException() method which you can use to handle the exception. The latter must return either true or false:
+
+*   If true: Magento handled the exception successfully. No need to do anything else.
+*   If false (or any other empty result): Magento did not handle the exception. The bootstrap object performs the default exception handling subroutine.
+
+*   Sends the response provided by the application object.
+
+![Magento Exam Information](./images/icon-info.png)A bootstrap is the program that initializes the operating system (OS) during startup. For Magento, it performs essential initialization routines, such as error handling, initializing the autoloader, setting profiling options, setting the default timezone, and other PHP config such as precision.
+
+![Magento Exam Question](./images/icon-question.png)**What is [`Magento\Framework\App\Bootstrap`](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/App/Bootstrap.php&sa=D&ust=1609223264558000&usg=AOvVaw10IOOWs76ZlVZZ8NT6niNs) used for?**
+
+1.  Configure autoloader (composer) - PSR-4 prepend `generation\Magento`
+2.  Calls object manager->create
+3.  Set error handlers
+4.  Assert maintenance
+5.  Assert installed
+6.  Starts the Magento application - bootstrap->createApplication()
+
+> Response = application->launch()
+> Response->sendResponse()
+> On error: application->catchException
+> On missed error:
+
+* Developer mode: prints exception trace
+* Production mode: log, message "An error has happened during application run. See exception log for details."
+
+![Magento Exam Information](./images/icon-info.png) Bootstrap run logic uses the following algorithm to run the Magento application:
+
+1.  Initializes the error handler.
+2.  Creates the object manager and basic shared services that are used everywhere and are affected by the environment. The environment parameters are injected properly into these objects.
+3.  Asserts that maintenance mode is not enabled; otherwise, terminates.
+4.  Asserts that the Magento application is installed; otherwise, terminates.
+5.  Starts the Magento application.
+
+![Magento Exam Question](./images/icon-question.png)**What are the following classes responsible for?**
+
+
+| Class Namespace | Entry Point | Description |
+|---|---|---|
+| `Magento\Framework\App\Http` | `index.php`, `pub/index.php` | Loads config area by front name then dispatches event: `controller_front_send_response_before `|
+| `Magento\Framework\App\Cron` | `pub/cron.php` | Config area "crontab" loads, then translations, then dispatches events. |
+| `Magento\MediaStorage\App\Media` | `pub/get.php` | Accesses `/media/*` directory when using DB image storage or a physical file doesn't exist. |
+| `Magento\Framework\App\StaticResource` | `pub/static.php` | In production/developer mode: get static asset by URL path `$area/$resource/$file` for example: `static/version1603322088/frontend/MyVendor/MyTheme/en_AU/jquery.min.js`. Also loads configuration by params and sends a file in response. In default mode: If file doesn't exist, generate it in class: `Magento\Framework\View\Asset\File::assetPublisher->publish` - materialize (copy/symlink) file if doesn't exist. |
+| `Magento\Indexer\App\Indexer` | `index.php`, `pub/index.php` | Regenerate all indexers - In Magento module `Magento_Indexer`. |
+
+![Magento Exam Information](./images/icon-info.png)Indexing is how Magento transforms data such as products and categories, to improve the performance. Original data entered to the system. Dictionaries are organized in [](http://en.wikipedia.org/wiki/Database_normalization&sa=D&ust=1609223264565000&usg=AOvVaw1Jl6Aj9LdVy7N4c-3iMHs0) [normal form](http://en.wikipedia.org/wiki/Database_normalization&sa=D&ust=1609223264566000&usg=AOvVaw3vcjAK-xbCrTaxEEi9mKRo) (data duplication) to facilitate maintenance (updating the data).
+
+Without indexing, Magento would have to calculate the price of every product on the fly, taking into account shopping [Cart Price Rules](#h.x0kvcqk03fp8), [Bundle Product](#h.41g7zcfrlmri) pricing, discounts, [tier pricing](#h.cw5qpmek3sj4), etc. Loading the price for a product would take a long time, possibly resulting in cart abandonment
+
+Magento\Backend\App\UserConfig
+
+Application for managing user configuration - module-backend
+
+2.1 Utilize modes and application initialization
+------------------------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**How would you design a customization that should act on every request and capture output data regardless of the controller?**
+
+Event: controller_front_send_response_before
+
+![Magento Exam Question](./images/icon-question.png)**Describe how to use Magento modes. What are the pros and cons of using developer mode/production mode?**
+
+php bin/magento deploy:mode:set production|developer|default
+
+![](./images/Magento2-Certification-Exam-Notes-Detailed-Insight-Deploy-Modes.png)
+
+Developer Mode
+
+*   Static file materialization is not enabled (not symlinked or generated on the fly).
+*   Uncaught exceptions displayed in the browser
+*   Exceptions thrown in error handler, not logged
+*   System logging in var/report, highly detailed.
+
+Production Mode
+
+*   Deployment phase on the production system; highest performance
+*   Exceptions are not displayed to the user -- written to logs only.
+*   This mode disables static file materialization (not symlinked or generated on the fly).
+*   The Magento docroot can have read-only permissions.
+
+Default Mode
+
+*   Used when no other mode is specified
+*   Hides exceptions from the user and writes them to log files
+*   Static file materialization is enabled.
+*   Not recommended / not optimized for production: caching impacts performance negatively.
+
+![Magento Exam Question](./images/icon-question.png)**When do you use default mode?**
+
+> As its name implies, default mode is how Magento operates if no other mode is specified. Default mode enables you to deploy the Magento application on a single server without changing any settings. However, default mode is not as optimized for production as is production mode.
+> In addition to [deployment processes above](#h.ape23zglcfl2)
+
+![Magento Exam Question](./images/icon-question.png)**How do you enable/disable maintenance mode?**
+
+```bash
+php bin/magento maintenance:enable
+php bin/magento maintenance:disable
+```
+
+![Magento Exam Question](./images/icon-question.png)**Describe front controller responsibilities. In which situations will the front controller be involved in execution, and how can it be used in the scope of customizations?**
+
+*   Front controller is only used in HTTP applications - pub/index.php i.e not used in CLI or API.
+*   Used in "frontend", "adminhtml", "webapi_rest", "webapi_soap" areas.
+*   It Gathers all routers (injected into the constructor using DI).
+*   Finds a matching controller/router.
+*   Obtains the generated HTML for the response object.
+
+> Front controller is the first step (entry point) for processing the flow of requests. Basically, the front controller controls all the other controllers. In Magento 2 it collects routes, matches the controllers, and receives the HTML generated for the response object (converting the query to a result). It is not used in areas such as the crontab/console.
+
+![Magento Exam Information](./images/icon-info.png)Some of these are obvious like "Front controller is only used in HTTP applications" but I think that is what they want to hear. You'll just have to memorise this.
+
+2.2 Demonstrate ability to process URLs in Magento
+--------------------------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**Describe how Magento processes a given URL.**
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)Front Controller
+
+> Routing in Magento 2 is based on Front Controller Pattern. Front Controller is a design pattern, in which one component is responsible for processing all the incoming requests, redirecting them to the corresponding components, further processing and returning the result to the browser. The FrontController iterates via the available routers and, if the action responsible for the current URL is successfully found, calls the method: `Magento\Framework\App\Action\AbstractAction::dispatch();`
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)Routers
+
+> All routers in Magento 2 should implement the interface: Magento\Framework\App\RouterInterface and define Magento\Framework\App\RouterInterface::match method. This method is responsible for matching and processing URL requests. In case of a successful match, the router returns the corresponding action instance. When the needed action is not found, the Front Controller is passed to the next router.
+
+> More on the types of Routers Magento has by default in section [2.3 Demonstrate ability to customize request routing](#h.1jz2h7ynseok).
+
+![](./images/Magento2-Certification-Exam-Notes-Detailed-Insight-Request-Layers.png)
+
+![Magento Exam Question](./images/icon-question.png)**How do you identify which module and controller corresponds to a given URL? What is necessary to create a custom URL structure?**
+
+```bash
+$routeName/$controllerName/$actionName/$param1/$value1/...
+```
+
+* `$routeName` = Search all modules routes.xml for the specified router name with the matching ID.
+* `$controllerName/$actionName` = Searches that Module router's ‘Controller' directory for the specified class (in camel-case). Modules for this ID are sorted with "before" and "after" attributes in the declarative schema.
+
+![Magento Exam Question](./images/icon-question.png)**Describe the URL rewrite process and its role in creating user-friendly URLs. How are user-friendly URLs established, and how are they customized?**
+
+Using Router urlrewrite:
+```
+?____from_store query param, redirects to a new URL if necessary.
+```
+
+> Example, on an English store category page /shoes switching to Norwegian store:
+> `/no/shoes?___from_store=1`
+> A new rewrite for norwegian store redirect to /no/sko (sko = norwegian for shoes)
+
+
+![Magento Exam Information](./images/icon-info.png) Just remember the urlrewrite Router is responsible for user friendly URLs and that you can customise them via the Admin & also by passing the query flag `?____from_store` in the URL.
+
+![Magento Exam Question](./images/icon-question.png)**Describe how action controllers and results function.**
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)Controllers
+
+> Controllers in Magento 2 differ from the typical MVC applications' controllers. In MVC applications, controller is a class, while action is the method of this class. In Magento 2, controller is a folder (or php namespace), while action is a class, located in this folder (in this php namespace). The execute method of the action returns the Result object and occasionally processes input POST data.
+
+> All actions inherit the class: [Magento\Framework\App\Action\Action](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/App/Action/Action.php%23L91&sa=D&ust=1609223264579000&usg=AOvVaw3LvjP894Vb4ZFtsSSymGM9).
+
+> Each Action should implement one or more Magento\Framework\App\Action\Http HTTPMethodActionInterface to declare which HTTP request methods it can process. The most common ones are:
+
+*   Magento\Framework\App\Action\HttpDeleteActionInterface
+*   Magento\Framework\App\Action\HttpGetActionInterface
+*   Magento\Framework\App\Action\HttpPostActionInterface
+*   Magento\Framework\App\Action\HttpPutActionInterface
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)Results
+
+> Actions in Magento 2 can return several response types depending on its purpose and desired result. More on this in the next question.
+
+> The following events are fired in [Magento\Framework\App\Action\Action::dispatch](https://github.com/magento/magento2/blob/2.3/lib/internal/Magento/Framework/App/Action/Action.php%23L91&sa=D&ust=1609223264581000&usg=AOvVaw0Bx1OPzG3N3QcyX0TFv7kk):
+
+*   Event: controller_action_predispatch
+*   Event: controller_action_predispatch_$routeName, e.g. ..._checkout
+*   Event: controller_action_predispatch_$fullActionName, e.g. ..._checkout_cart_index
+*   Stop if FLAG_NO_DISPATCH
+*   Execute - all action controllers that implement App\Action\Action
+*   Stop if FLAG_NO_POST_DISPATCH
+*   Event: controller_action_postdispatch_$fullActionName
+*   Event: controller_action_postdispatch_$routeName
+*   Event: controller_action_postdispatch
+*   If action doesn't return result, response object is returned -- action just modifies response object
+
+![Magento Exam Information](./images/icon-info.png) Just remember Controllers handle HTTP requests (PUT POST GET DELETE etc) and Results return responses in various formats depending on the desired outcome (see below for various types).
+
+![Magento Exam Question](./images/icon-question.png)**How do controllers interact with other controllers?**
+
+> A Controller can interact with another via 2 ways:
+
+1. A Redirect, for example Magento\Framework\Controller\Result\Redirect\Factory:
+```php
+public function __construct(
+        Magento\Framework\Controller\Result\Redirect\Factory $resultRedirectFactory
+) {
+        $this->resultRedirectFactory = $resultRedirectFactory;
+}
+
+public function execute()
+{
+        $result = $this->resultRedirectFactory->create();
+        $result->setPath('*/*/index');
+        return $result;
+}
+```
+2. A Forward Result, less commonly used. Example
+```php
+public function __construct(
+    Magento\Framework\Controller\Result\Forward\Factory $resultForwardFactory
+) {
+    $this->resultForwardFactory = $resultForwardFactory;
+}
+
+public function execute()
+{
+    $result = $this->resultForwardFactory->create();
+    $result->forward('noroute');
+    return $result;
+}
+```
+
+![Magento Exam Information](./images/icon-info.png)Just remember Forward Result, Redirect Result.
+
+![Magento Exam Question](./images/icon-question.png)**How are different response types generated?**
+
+> Action in Magento 2 can return several response types depending on its purpose and desired result. All actions returned results inherit class Magento\Framework\Controller\AbstractResult and can be in the form of:
+
+*   `Magento\Framework\Controller\Result\Json` - A possible implementation of JSON response type (instead of hardcoding `json_encode()` all over the place). An actual for controller actions that serve ajax requests.
+
+*   `Magento\Framework\Controller\Result\Redirect` - In many cases controller actions may result in a redirect so this is a result object that implements all necessary properties of a HTTP redirect.
+
+*   `Magento\Framework\Controller\Result\Forward` - Internally calls the execute method of another action class and does not trigger a new request from the browser. The URL stays the same.
+
+*   `Magento\Framework\Controller\Result\Raw` - A result that contains raw response - may be good for passing through files, returning result of downloads or some other binary contents.
+
+*   `Magento\Framework\View\Result\Page` - A "page" result that encapsulates page type, page configuration and imposes certain layout handles.The framework convention is that there will be loaded a guaranteed handle for "all pages", then guaranteed handle that corresponds to page type and a guaranteed handle that stands for page layout (a wireframe of a page) Page result is a more specific implementation of a generic `Magento\Framework\View\Result\Layout` response.
+
+![Magento Exam Information](./images/icon-info.png) Just remember Forward Result, Redirect Result, Page Result & Raw Result.
+
+2.3 Demonstrate ability to customize request routing
+----------------------------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**Describe request routing and flow in Magento.**
+
+Frontend
+| Name | Sort order | Description |
+| --- | --- | --- |
+| [`robots`](https://github.com/magento/magento2/blob/2.2/app/code/Magento/Robots/Controller/Router.php&sa=D&ust=1609223264592000&usg=AOvVaw1t7io0nRyaTo8gasoexM8U) | 10 | Matches request to the robots.txt file |
+| [`urlrewrite`](https://github.com/magento/magento2/blob/2.2/app/code/Magento/UrlRewrite/Controller/Router.php&sa=D&ust=1609223264593000&usg=AOvVaw22YRzy-U_ItCidN7DYEXGQ) | 20 | (`Magento\UrlRewrite\Controller\Router`) is responsible for catalog URL rewrites. It uses Url Finder to find the necessary URL in the database, and after that returns the forward just like CMS Router. |
+| [`standard`](https://github.com/magento/magento2/blob/2.2/lib/internal/Magento/Framework/App/Router/Base.php&sa=D&ust=1609223264595000&usg=AOvVaw1hhz8s0DW3y1I5uN-lQ0H5) | 30 | A.K.A Base Router: (Magento\Framework\App\Router\Base) sets module front name, controller and action names, controller module and route name if found. Processes standard Magento URLs. |
+| [`cms`](https://github.com/magento/magento2/blob/2.2/app/code/Magento/Cms/Controller/Router.php&sa=D&ust=1609223264596000&usg=AOvVaw0YUrT_xasXuzgFLED_Yhnu) | 60 | (`Magento\Cms\Controller\Router`) is used for processing CMS pages. Sets module name to "cms", controller name to "page", action name to "view" and page id depending on the requested page. After that it forwards request but won't dispatch it. This will lead to Front Controller starting the next cycle of router checking, on which Base Router based on the established path will call. |
+| [`default`](https://github.com/magento/magento2/blob/2.2/lib/internal/Magento/Framework/App/Router/DefaultRouter.php&sa=D&ust=1609223264598000&usg=AOvVaw1DBtgglBYdbj48Af1bsW3m) | 100 | (`Magento\Framework\App\Router\DefaultRouter`) is used when no other router is able to find the appropriate controller. It's responsible for 404 Page. |
+
+
+Backend
+| Name | Sort order | Description |
+| --- | --- | --- |
+| [`admin`](https://github.com/magento/magento2/blob/2.2/app/code/Magento/Backend/App/Router.php&sa=D&ust=1609223264601000&usg=AOvVaw1sRf8fxedsrSVDLltAhBeB) | 10 | Matches requests in the Magento admin area |
+| [`default`](https://github.com/magento/magento2/blob/2.2/lib/internal/Magento/Framework/App/Router/DefaultRouter.php&sa=D&ust=1609223264602000&usg=AOvVaw1G2Jvo4C4Oriq1WCAPbq4N) | 100 | The default router for the admin area |
+
+
+![Magento Exam Question](./images/icon-question.png)**When is it necessary to create a new router or to customize existing routers?**
+
+> Very rarely would you need to create a new router, usually the above routers are fine. Only when the URL structure doesn't fit into the module/controller/action template, e.g. fixed robots.txt or dynamic arbitrary rewrites from DB.
+
+![Magento Exam Question](./images/icon-question.png)**How do you handle custom 404 pages?**
+
+1.  If the front controller catches `Magento\Framework\Exception\NotFoundException`, it changes the action name "noroute" and continues the loop. E.g. catalog/product/view/id/1 throws NotFoundException. catalog/product/noroute is checked.
+2.  If the standard router recognizes the front name but can't find the controller, it tries to find the "noroute" action from the last checked module. E.g. catalog/brand/info controller doesn't exist, so catalog/brand/noroute will be checked.
+3.  If all routers didn't match, default controller provides two opportunities:
+    *  set default 404 route in admin config web/default/no_route (see: `Magento\Framework\App\Router\NoRouteHandler::process`)
+    *  Register custom handler in noRouteHandlerList:
+    backend (sortOrder: 10) Magento\Backend\App\Router\NoRouteHandler -> adminhtml/noroute/index
+    default (sortOrder: 100) Magento\Framework\App\Router\NoRouteHandler
+
+2.4 Determine the layout initialization process
+-----------------------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**Determine how layout is compiled.**
+
+> Layout XML (layout.xml) is generated by compiling via Dependency Injection. Specifically: all the available handles for each route are built, loaded, generated, configured and returned. In further detail:
+
+1. Core Magento Framework Layout classes are built:
+    * `Magento\Framework\View\Layout::build();`
+    * `Magento\Framework\View\Layout\Builder::build();`
+    * `Magento\Framework\View\Model\Layout\Merge::load();`
+
+2. Handles from the var $handles to the protected field $handles are added. This is how they are generated:
+    * A physical theme, based on the current theme, is loaded. Physical is the theme that has a designated folder and which is loaded via registration.php. There are TYPE_PHYSICAL=0, TYPE_VIRTUAL=1, TYPE_STAGING=2 types stored in "theme" table of the database.
+    * The search of all *.xml files in the folders layout, page_layout in all enabled modules and current themes.
+    * A new xml tag (handle or layout) is added into $layoutStr variable/property.
+    * From this xml only necessary handles are loaded.
+    * Additional handles from the database are loaded.
+
+3. Layout for the current handles is returned.
+4. XML object and configuration generated.
+
+![Magento Exam Information](./images/icon-info.png) Just remember that Layout XML (`layout.xml`) is generated by compiling via Dependency Injection, all the available handles for each route is built, loaded, generated, configured and returned in the Magento_Framework module.
+
+![Magento Exam Question](./images/icon-question.png)**How would you debug your `layout.xml` files and verify that the right layout instructions are used?**
+
+
+1. You can create an Observer using the layout_generate_blocks_after event to dump out the XML:
+```xml
+<?xml version="1.0" encoding="UTF-8"?>
+
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
+   <event name="layout_generate_blocks_after">
+       <observer name="vendor_module_layout_generate_blocks" instance="MyVendor\MyModule\Observer\LayoutGenerateBlockObserver" />
+   </event>
+</config>
+```
+
+```php
+public function execute(Observer $observer)
+{
+    header('Content-Type: text/xml');
+    $layoutString = $observer->getEvent()->getLayout()->getXmlString();
+    echo '<layouts xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">' . $layoutString . '</layouts>';
+    die;
+}
+```
+
+2. You can also temporarily dump out the page layout / XML in the execute method of a Controller Action before the return element:
+
+```php
+header('Content-Type: text/xml');
+$layoutString = $resultPage->getLayout()->getXmlString();
+echo '<layouts xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">' . $layoutString . '</layouts>';
+die;
+```
+![Magento Exam Information](./images/icon-info.png)This is actually pretty useful to use practically.
+
+![Magento Exam Question](./images/icon-question.png)**Determine how HTML output is rendered.**
+
+For layout rendering:
+*   `Magento\Framework\View\Layout::getOutput()` is called. This method recursively renders every registered _output child element.
+*   `Magento\Framework\View\Layout::renderElement`
+
+![Magento Exam Information](./images/icon-info.png)This is what happens up the tree when you call `getChildHtml()` / `_toHtml()` from your block class.
+
+![Magento Exam Question](./images/icon-question.png)**How does Magento flush output, and what mechanisms exist to access and customize output?**
+
+> The [Front Controller](#h.1rr8cbug1ad) returns a response to App\Bootstrap by calling Action Controllers. Action Controllers return certain $result which are [specified in section 2.2](#h.39aby0sbkm32). There can be different types of `$result`; for instance:
+
+*  `Magento\Framework\Controller\Result\Raw`
+*  `Magento\Framework\Controller\Result\Json`
+*  `Magento\Framework\Controller\Result\Redirect`
+*  `Magento\Framework\View\Result\Layout`
+*  `Magento\Framework\View\Result\Page`
+
+During this process 2 events are fired:
+
+1.  `Magento\Framework\App\Http` event: `controller_front_send_response_before`
+2.  `Magento\Framework\View\Element\AbstractBlock::toHtml` event: `view_block_abstract_to_html_after`
+
+> That allows you to modify responses before returning. Depending on the $result type, Magento flushes html output the following way:
+1.  [Controller Action](#h.39aby0sbkm32) returns certain $result type (above).
+2.  If result is instance of `Magento\Framework\App\Response\HttpInterface`, then the result is returned to the browser
+3.  Otherwise, in case result is instance of `Magento\Framework\Controller\ResultInterface`, then:
+    *  `$result->renderResult($response)` is called, which calls `$result->applyHttpHeaders($response)` and `$result->render($response)`
+    *  Then, `$response->sendResponse()` method is called. The method sends headers and body to the browser.
+
+![Magento Exam Information](./images/icon-info.png)Just remember that Magento flushes output depending on the result type returned, therefore manipulating the relevant [Controller Action](#h.39aby0sbkm32) would be how you customise output.
+
+![Magento Exam Information](./images/icon-info.png)Event controller_front_send_response_before seems to pop-up A LOT in the exam notes, I would remember this.
+
+![Magento Exam Question](./images/icon-question.png)**How do you add new elements to the pages introduced by a given module?**
+
+Module layouts:
+
+```
+<module_dir>/view//layouts.xml
+<theme_dir>/_/layouts.xml
+```
+
+base:
+```
+empty
+```
+
+frontend:
+```
+ 1column - extends empty
+ 2columns-left - extends 1column
+ 2columns-right - same as 2columns-left
+ 3columns - same as 2columns-left
+```
+
+adminhtml:
+```
+ admin-empty
+ admin-1column
+ admin-2columns-left
+```
+
+![Magento Exam Information](./images/icon-info.png)Remember that the layouts.xml file is responsible for the base column layouts i.e 1column, 2columns-left etc.
+
+![Magento Exam Question](./images/icon-question.png)**Determine module layout XML schema.**
+
+Schema using `urn:magento:framework:View/Layout/etc/layout_generic.xsd`
+
+| Element | Attributes | Parent of | Description |
+| --- | --- | --- | --- |
+| `<layout>` | `xsi:noNamespaceSchemaLocation="{path_to_schema}"` | `<container>`, `<update>` | Mandatory element |
+| `<update>` | `handle="{name_of_handle_to_include}"` | None | |
+| `<container>` | For complete list of attributes, see [](https://devdocs.magento.com/guides/v2.3/frontend-dev-guide/layouts/xml-instructions.html%23fedg_layout_xml-instruc_ex_cont&sa=D&ust=1609223264632000&usg=AOvVaw0xP9WfcYwPmjrhnlVBnK0-) [Layout instructions](https://devdocs.magento.com/guides/v2.3/frontend-dev-guide/layouts/xml-instructions.html%23fedg_layout_xml-instruc_ex_cont&sa=D&ust=1609223264633000&usg=AOvVaw0C1fP3AdUmV7BLrkImmYqK) | `<block>`, `<container>`, `<referenceBlock>`, `<referenceContainer>` | Mandatory element |
+
+![Magento Exam Information](./images/icon-info.png)This is essentially a basic definition of a page XML layout handle, think of some of the parent/root elements of layout checkout_index_index.xml and you got it.
+
+Schema `page_configuration.xsd`
+
+| Element | Attributes | Parent of | Description |
+| --- | --- | --- | --- |
+| `<page>` | `layout = {layout}`, `xsi:noNamespaceSchemaLocation="{path_to_schema}"` | `<html>`, `<head>`, `<body>`, `<update>` | Mandatory root element.
+| `<html>` | None | `<attribute>` | |
+| `<head>` | `name="root"` For complete list of attributes, see [here](https://devdocs.magento.com/guides/v2.3/frontend-dev-guide/layouts/xml-instructions.html%23fedg_layout_xml-instruc_ex_cont&sa=D&ust=1609223264640000&usg=AOvVaw0Sy1hiN8ycGNfJR_NWHrBI). [Layout instructions](https://devdocs.magento.com/guides/v2.3/frontend-dev-guide/layouts/xml-instructions.html%23fedg_layout_xml-instruc_ex_cont&sa=D&ust=1609223264641000&usg=AOvVaw0WKrH13QavLIgsryLCp6Ch) | `<title>`, `<meta>`, `<link>`, `<css>`, `<font>`, `<script>` | Mandatory element |
+| `<body>` | None | `<block>`, `<container>`, `<move>`, `<attribute>`, `<referenceBlock>`, `<referenceContainer>`, `<action>` | |
+| `<attribute>` | name = {arbitrary_name}, value = {arbitrary_value} | | |
+| `<title>` | None | None | Page title |
+| `<meta>` | content, charset, http-equiv, name, scheme | None |
+| `<link>` | defer, ie_condition, charset, hreflang, media, rel, rev, sizes, src, src_type, target, type | None | |
+| `<css>` | defer, ie_condition, charset, hreflang, media, rel, rev, sizes, src, src_type, target, type | None | |
+| `<script>` | defer, ie_condition, async, charset, src, src_type, type | None | |
+
+![Magento Exam Information](./images/icon-info.png)This page_configuration.xsd is essentially just the schema of a standardised HTML document only it's XML format.
+
+layouts.xml - declare available page layouts
+
+| Directory | Sort Order |
+| --- | --- |
+| `<theme_dir>/<Namespace>_<Module>/layouts.xml` | 1 |
+| `<module_dir>/view/<area_code>/layouts.xml` | 2 |
+
+Examples:
+
+*   base:
+    *   empty
+*   frontend:
+    *   1column - extends empty`
+    *   2columns-left - extends 1column
+    *   2columns-right - same as 2columns-left
+    *   3columns - same as 2columns-left`
+*   adminhtml:
+    *   admin-empty
+    *   admin-1column
+    *   admin-2columns-left
+
+Schema `page_layout.xsd`
+> Page layout declares the wireframe of a page inside the <body> section, for example one-column layout or two-column layout. Allowed layout instructions:
+
+*   [`<container>`](https://devdocs.magento.com/guides/v2.3/frontend-dev-guide/layouts/xml-instructions.html%23fedg_layout_xml-instruc_ex_cont&sa=D&ust=1609223264658000&usg=AOvVaw2Kkck3YgOrzUnrJYS-Fntv)
+*   [`<referenceContainer>`](https://devdocs.magento.com/guides/v2.3/frontend-dev-guide/layouts/xml-instructions.html%23fedg_layout_xml-instruc_ex_ref&sa=D&ust=1609223264658000&usg=AOvVaw1mhX4p66cLtYOB5tdzDMJ4)
+*   [`<move>`](https://devdocs.magento.com/guides/v2.3/frontend-dev-guide/layouts/xml-instructions.html%23fedg_layout_xml-instruc_ex_mv&sa=D&ust=1609223264659000&usg=AOvVaw05MW2PUfH5BHcLsLzAr_Z8)
+*   [`<update>`](https://devdocs.magento.com/guides/v2.3/frontend-dev-guide/layouts/xml-instructions.html%23fedg_layout_xml-instruc_ex_upd&sa=D&ust=1609223264659000&usg=AOvVaw05lwHgwtA5VN1-bEa4jdOS)
+
+![Magento Exam Information](./images/icon-info.png)Sample page layout: <Magento_Theme_module_dir>/view/frontend/page_layout/2columns-left.xml
+
+![Magento Exam Question](./images/icon-question.png)**How do you add new elements to the pages introduced by a given module?**
+
+```xml
+<block class="module\block\class" template="new module template" ... />
+```
+
+![Magento Exam Information](./images/icon-info.png)Think "block" rather than "element" then this will give you a hint
+
+![Magento Exam Question](./images/icon-question.png)**Demonstrate the ability to use layout fallback for customizations and debugging.**
+
+```
+View\Element\Template::getTemplateFile
+
+            V
+
+View\Element\Template\File\Resolver::getTemplateFileName(template, [module, area]) Caches in memory
+
+            V
+
+View\FileSystem::getTemplateFileName
+
+            V
+
+View\Asset\Repository::updateDesignParams
+
+            V
+
+Detects module by Module_Name::template.phtml, adds default params
+
+            V
+
+Adds default missing params [object themeModel, locale]
+
+            V
+
+View\Design\FileResolution\Fallback\TemplateFile::getFile(area)
+
+            V
+
+View\Design\FileResolution\Fallback\File::getFile
+
+            V
+
+View\Design\FileResolution\Fallback\Resolver\Simple::resolve
+
+            V
+
+View\Design\Fallback\RulePool::getRule
+
+            V
+
+View\Design\FileResolution\Fallback\Resolver\Simple::resolveFile(fileRule)
+```
+
+
+File fallback rule
+
+| Directory | Sort Order | Condition |
+| --- | --- | --- |
+| `<theme_dir>` | 1 | When missing 'module_name' e.g. "app/design/frontend/Theblockshop/theblockshop" |
+| `<theme_dir>/<module_name>/templates` | 2a | When set 'module_name' e.g. "app/design/frontend/Theblockshop/theblockshop/Magento_Checkout" |
+| `<module_dir>/view/<area_code>/templates` | 2b | When set 'module_name' e.g. "app/code/Convert/EstimateShipping/view/frontend/templates" |
+| <module_dir>/view/base/templates | 2c | When set 'module_name' e.g. "app/code/Convert/EstimateShipping/view/base/templates" |
+
+![Magento Exam Information](./images/icon-info.png)Just remember the File fallback rule and the class `Magento\Framework\View\Element\Template::getTemplateFile`  - I think it would be cruel if they made you resight class names… There are 1000s
+
+![Magento Exam Question](./images/icon-question.png)**How do you identify which exact layout.xml file is processed in a given scope?**
+
+* Determine which area is loaded (frontend or adminhtml).
+* Locate the layout handle.
+* Search through the project to find all XML files with that name.
+
+> Alternatively, add the following code into the [Controller Action](#h.39aby0sbkm32) into the execute method before return:
+
+```php
+var_dump($resultPage->getLayout()->getUpdate()->getHandles()); die;
+```
+![Magento Exam Information](./images/icon-info.png)Similar to the above question.
+
+![Magento Exam Question](./images/icon-question.png)**How does Magento treat layout XML files with the same names in different modules?**
+
+> Magento merges the layout xml files into a single one during [Dependency Injection](#h.9ofwnl5q9fnf) (DI) compilation.
+
+> XML of the same file names are merged according to tag names (for example: `<block>`) and the id="" attributes.
+
+> The order in which they merge depend on both the File Fallback rule & Module Sequence. For example:
+
+*   Modules that depend on other modules are merged in Module sequence order: the `<sequence>` tag defined in each `<module_dir>/etc/module.xml`
+*   Layout XML files in the theme directory app/design take precedence over those in the app/code directory (Modules).
+
+![Magento Exam Question](./images/icon-question.png)**Identify the differences between admin and frontend scopes. What differences exist for layout initialization for the admin scope?**
+
+> An area is a logical component that organizes code for optimized request processing. Magento uses areas to streamline web service calls by loading only the dependent code for the specified area. Each of the default areas defined by Magento can contain completely different code on how to process URLs and requests.
+
+Features - These are the functional differences between admin and frontend:
+
+*   ACL permissions - _isAllowed, change static const ADMIN_RESOURCE
+*   Base controllers are different
+  *   Frontend: `Magento\Framework\App\Action`
+  *   Admin: `Magento\Backend\App\AbstractAction`
+*   Custom URL model which uses a secret key: key
+*   The layout acl block attribute
+*   File tree path structures are different:
+  *   app/design/adminhtml vs app/design/frontend
+  *   `<module_dir>/view/adminhtml` vs `<module_dir>/view/frontend`
+*   UIComponents are used in Adminhtml whereas they are not in Frontend.
+*   The adminhtml area code (of Magento\Framework\App\Area) includes and allows code needed for store management (using Magento\Framework\App\State) whereas frontend  contains template and layout files that define the appearance of your storefront only.
+
+Scope Properties  -To better answer this particular question and the differences between admin/frontend scopes for layout initialization these are the main differences:
+
+*   Layout area is different when searching file paths:
+    *   Admin: adminhtml
+    *   Frontend: frontend
+*   The default Block classes are different:
+    *   Frontend: `Magento\Backend\Block\AbstractBlock`
+    *   Frontend: `Magento\Backend\Block\Template`
+*   The layout area aclResource support is added for admin, allowing you to connect the resource to a block and hide the block if the user does not have access to the resource.
+*   Some extra properties are available in admin
+    *   authorization
+    *   mathRandom
+    *   backendSession
+    *   formKey
+    *   class nameBuilder
+*   Different events are dispatched for example:
+    *   Admin: adminhtml_block_html_before - fired only when non-cached render.
+    *   Frontend: to compare, event `view_block_abstract_to_html_after` fires even when block loaded from cache
+*   [Controller Result](#h.39aby0sbkm32) object has different methods:
+    *   setActiveMenu
+    *   addBreadcrumb
+    *   addContent(block) - moves to 'content'
+    *   addLeft(block)
+    *   addJs
+    *   moveBlockToContainer
+
+![Magento Exam Information](./images/icon-info.png)Adminhtml & Frontend do share functionality also such as design paths in <module_dir>/view/base & app/design/base if common functionality exists between them.
+
+2.5 Determine The Strucuture Of Block Templates
+----------------------------------------------
+
+> Page structures are defined by the layout in the page layout nodes. An example can be seen in the `catalog_product_view.xml`
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)Root Template
+
+> The root template is the most basic piece and common conglomeration of HTML that is possible in Magento. It is where the result of the layout instructions are put.
+>
+> Magento only has one root template: `vendor/magento/module-theme/view/base/templates/root.phtml`.
+>
+> This file is injected into the controller’s Page result (`vendor/magento/module-theme/view/base/templates/root.phtml`) with dependency injection:
+>
+> * `vendor/magento/module-backend/etc/adminhtml/di.xml`
+> * `vendor/magento/magento2-base/app/etc/di.xml`
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)`empty.xml`
+
+> This is the parent page layout XML file. All page layout files derive and extend this.
+
+
+![Magento Answer Section - Chevron](./images/icon-chevron.png)`page_layout`
+
+> Files in these directories represent different page layout ideas. For example, Magento comes with a 1 column layout, a 2 column (right or left) layout, and a 3 column layout (found in vendor/magento/module-theme/view/frontend/page_layout).
+>
+> You can create new layout types by simply adding a new file in a `view/frontend/page_layout` directory.
+
+
+![Magento Exam Question](./images/icon-question.png)**How are page structures defined, including number of columns, which basic containers are present, etc.?**
+
+> To specify a layout for a page, wrap the XML file in a `<page/>` node and set the `layout=""`
+
+> By adding a container to the columns container. Containers are powerful in that you can specify the HTML tag name and associate classes.
+
+Examples:
+
+* `vendor/magento/module-theme/view/frontend/page_layout/1column.xml`
+* `vendor/magento/module-theme/view/frontend/page_layout/3columns.xml`
+
+
+![Magento Exam Question](./images/icon-question.png)**Describe the role of blocks and templates in the request flow. In which situations would you create a new block or a new template?**
+
+> A `ViewModel` can be used to provide data to a template (`.phtml` file). In most cases, creating a custom block type is no longer necessary. The block includes the template, and shares the view model for data retrieval.
+>
+> You do not need to specify a block’s type in layout XML anymore. The default `\Magento\Framework\View\Element\Template` is specified in the absence of the type attribute. Instead, specifying the view_model argument is the way that Magento now recommends.
+>
+> Two cases where creating a block is necessary would be:
+>
+> * If the template is determined at runtime (cart item renderers).
+> * Or non-default block caching needs to be used.
+>
+> Templates are created to display information. For module development, templates and blocks represent an almost 1:1 ratio. For theme development, many more templates will be created or overridden than blocks.
\ No newline at end of file
diff --git a/3. Customizing the Magento UI/1. Demonstrate ability to utilize themes and the template structure.md b/3. Customizing the Magento UI/1. Demonstrate ability to utilize themes and the template structure.md
deleted file mode 100644
index 3e1e5e8..0000000
--- a/3. Customizing the Magento UI/1. Demonstrate ability to utilize themes and the template structure.md	
+++ /dev/null
@@ -1,317 +0,0 @@
-# Demonstrate ability to utilize themes and the template structure
-
-app/design/frontend/Vendor/themename/
-```
-- composer.json
-- registration.php
-- theme.xml - name, parent, logo
-- etc/view.xml - currently catalog images configuration
-- i18n/
-- media/ - pub logo here
-- Magento_Checkout/ - extend specific module
----- layout/ - normally layouts are extended
-------- override/base/ - special case: completely replace base layout for module
-------- override/theme/Magento/luma/ - special case: completely replace specific theme layout
----- templates/ - replace module files
----- web/ - replace module files
-- web/ - replace theme files
----- js/
----- css/
-------- source/
----- fonts/
----- images/
----- i18n/en_US/ - locale-specific file replacement (without module)
----- i18n/en_US/Magento_Checkout/ - locale-specific module file replacement
-```
-
-- Magento\Theme\Model\View\Design implements View\DesignInterface
-- View\Model\Layout\Merge implements View\Layout\ProcessorInterface
-
-## Layouts:
-
-Normally layouts are merged, extending parent ones.
-
-To completely replace *original module layout* file, e.g. to replace
-vendor/magento/module-checkout/view/frontend/layout/default.xml place new file in
-Magento_Checkout/layout/override/base/default.xml
-
-To completely replace some *parent theme's layout* customization, e.g. to replace
-vendor/magento/theme-frontend-luma/Magento_Checkout/layout/default.xml place new file in
-Magento_Checkout/layout/override/Magento/luma/default.xml
-
-It is *not possible* to use override trick inside *module*, only in theme. You cannot create
-new module app/code/MyVendor/MyModule/view/frontend/layout/override/... and replace layout files.
-
-## Locale:
-
-You can replace static files with locale-specific - JS, logo, font etc. You have 2 places:
-- non-module specific, e.g. theme asset - web/i18n/en_US/
-- from some module - web/i18n/en_US/Magento_Checkout/ 
-
-### how is theme loaded
-- plugin magento-store/etc/di.xml
-- App\Action\AbstractAction.beforeDispatch
-- View\DesignLoader::load
-- App\Area::load('design')
-- App\Area::_initDesign
-  * singleton View\DesignInterface = \Magento\Theme\Model\View\Design
-  * design.setArea('frontend')
-  * design.getConfigurationDesignTheme
-  * design.setDefaultDesignTheme
-    + get config `design/theme/theme_id` (website scope if single store mode, otherwise store view scope)
-    + EE only: if theme is not configured, use default from DI argument Magento/luma
-  * design.setDesignTheme - area, theme model. loads theme model from DB
-    + View\Design\Theme\FlyweightFactory::create
-    + View\Design\Theme\ThemeProviderInterface::getThemeByFullPath
-      Has 2 implementations, real DB and fake data collection - Can be used to deploy static or
-      in other setup commands, even if Magento is not installed yet.
-
-
-singleton *View\DesignInterface* = \Magento\Theme\Model\View\Design - holds current area, locale and theme model
-- get/setDesignTheme = theme
-- get/setArea
-- getLocale
-- getConfigurationDesignTheme
-- setDefaultDesignTheme
-- getThemePath
-- getDesignParams - area, theme, locale
-
-*View\Design\ThemeInterface* = \Magento\Theme\Model\Theme - this is also DB model
-- getArea
-- getCode
-- getParentTheme
-- getInheritedThemes
-- getId
-- getThemePath
-- getFullPath
-- isPhysical
-
-*Theme type*: physical, virtual, staging
-
-_Physical themes_
-
-Physical refers to the fact that those themes are defined by files.
-For example, the blank and luma theme are physically defined under app/design/frontend/
-
-_Virtual themes_
-
-This is yet unclear but I think virtual themes refer to themes you can create in the
-backend which extends existing physical themes but it seems like it's not fully implemented yet.
-You can see that there's two tabs available in the edit section only for virtual themes which let
-you provides custom CSS and JS for a virtual theme.
-I reckon a virtual theme would be something you setup temporarily (like Christmas theme) for a short
-period of theme and which requires only few design changes compared to the physical theme it extends.
-
-_Staging_
-
-Must be something about EE campaign.
-
-
-### how loadLayoutUpdates works
-
-- Loads ALL layout update files using file name as layout handle name - as XML object.
-- Selects only currently relevant handles (e.g. 'default', 'checkout_cart_index').
-- Finds <update handle=name> instructions, merges them recursively.
-- Selected file contents as added to `_updates[]` array as pieces of string - they will
-be converted to XML object later in generateLayoutXml.
-
-Trace:
-
-View\Layout\Builder::loadLayoutUpdates
-  * event `layout_load_before`
-  * View\Model\Layout\Merge::load
-    + Collects loaded layout files contents into `updates[]` array.
-    + Loads from cache when possible, XML contents (e.g. '<block name="someBlock" ....><referenceBlock....>')
-      and separately pageLayout (e.g. '1column')
-
-merge.load(handle)
-- merge._merge(handle)
-
-  * Called for every page handle, e.g. 'default', 'checkout_cart_index'.
-  * Checks cyclic dependency - logs error in dev mode
-  * _fetchPackageLayoutUpdates
-  * _fetchDbLayoutUpdates
-  
-- merge._validateMergedLayout
-  * View\Model\Layout\Update\Validator::isValid with `urn:magento:framework:View/Layout/etc/layout_merged.xsd`
-  
-
-*_fetchPackageLayoutUpdates*
-  * merge.getFileLayoutUpdatesXml - loads ALL layouts regardless of handle
-      * merge._loadFileLayoutUpdatesXml
-        - get physical theme, checking parents until found
-        - update files = theme file source.getFiles + page layout file source.getFiles
-        - read files one by one
-        - merge._substitutePlaceholders - replaces in raw XML string - {{baseUrl}} and {{baseSecureUrl}}
-        - adds file contents to result as one of:
-
-        ```xml
-              <layout id="{$fileName}" {$attributes}>{$fileContents}</layout>
-              <handle id="{$fileName}" {$attributes}>{$fileContents}</handle>
-        ```
-
-        - all are wrapped in outer tag
-
-        ```xml
-              <layouts xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
-                <layout id="default" {$attributes}>{$fileContents}</layout>
-                <handle id="checkout_cart_index" {$attributes}>{$fileContents}</handle>
-                <handle id="checkout_cart_index">{$fileContents}</handle>
-                ...
-              </layouts>
-        ```
-
-  * finds all <layout> and <handle> with ID *matching handle* that is being loaded
-      * merge._fetchRecursiveUpdates - finds xpath <update handle="any">, calls _merge recursively
-      * merge.validateUpdate 
-          plugin \Magento\PageCache\Model\Layout\MergePlugin::beforeValidateUpdate checks that entity-specific
-          update handles don't have `ttl` declarations
-      * merge.addUpdate -- main goal, adds content to `updates[]`
-
-*_fetchDbLayoutUpdates:*
-  * does nothing itself, but there's a plugin
-    \Magento\Widget\Model\ResourceModel\Layout\Plugin::aroundGetDbUpdateString - loads updates from DB by theme/store
-  * merge._fetchRecursiveUpdates - finds xpath <update handle="any">, calls _merge recursively
-  * merge.validateUpdate 
-  * merge.addUpdate
-
-
-
-### Layout file source
-
-merge.*fileSource*:
-View\Layout\File\Collector\Aggregated\Proxy - Source of layout files aggregated from a theme
-and its parents according to merging and overriding conventions
-
-- add *base files* - modules
-
-  * View\File\Collector\Decorator\ModuleDependency as layoutFileSourceBaseSorted
-  * View\File\Collector\Decorator\ModuleOutput as layoutFileSourceBaseFiltered
-  * *View\File\Collector\Base* as layoutFileSourceBaseFiltered, subDir = 'layout'
-  * Component\DirSearch::collect(type='module', pattern) - uses component registrar to get modules, then searches by pattern
-
-```
-    <modules>/view/base/layout/*.xml --- isBase = true, shared between adminhtml and frontend themes
-    <modules/view/frontend/layout/*.xml
-```
-
-- get inherited themes
-
-for each theme (e.g. Magento/blank, then Magento/luma):
-- add theme files
-
-  * View\File\Collector\Decorator\ModuleDependency as layoutFileSourceThemeSorted
-  * View\File\Collector\Decorator\ModuleOutput as layoutFileSourceThemeFiltered
-  * *View\File\Collector\ThemeModular* as layoutFileSourceTheme, subDir = 'layout'
-
-```
-    <theme>/*_*/layout/*.xml -- sets module context, e.g. Magento_Checkout
-```
-
-- replace override base files
-
-  * View\File\Collector\Decorator\ModuleDependency as layoutFileSourceOverrideBaseSorted
-  * View\File\Collector\Decorator\ModuleOutput as layoutFileSourceOverrideBaseFiltered
-  * *View\File\Collector\Override\Base* as layoutFileSourceOverrideBase, subDir = 'layout/override/base'
-
-```
-    <theme>/*_*/layout/override/base/*.xml
-```
-
-  * View\File\FileList::replace
-  * View\File\FileList\Collator::collate - replaces by matching keys: is base, theme, module, filename
-
-- replace override theme files
-
-  * View\File\Collector\Decorator\ModuleDependency as layoutFileSourceOverrideThemeSorted
-  * View\File\Collector\Decorator\ModuleOutput as layoutFileSourceOverrideThemeFiltered
-  * *View\File\Collector\Override\ThemeModular* as layoutFileSourceOverrideTheme, subDir = 'layout/override/theme'
-
-```
-    <theme>*_*/layout/override/theme/*/*/*.xml
-```
-
-
-### Page layout file source
-
-All same as layout, but subDir 'page_layout':
-
-```
-    <modules>/view/base/page_layout/*.xml --- isBase = true, shared between adminhtml and frontend themes
-    <modules/view/frontend/page_layout/*.xml
-    <theme>/*_*/page_layout/*.xml -- sets module context, e.g. Magento_Checkout
-    <theme>/*_*/page_layout/override/base/*.xml
-    <theme>*_*/page_layout/override/theme/*/*/*.xml
-```
-
-View\Layout\ProcessorInterface = View\Model\Layout\Merge
-- $updates - array of all found string XML file contents E.g.
-```
-  updates[] = '<body><block name="someBlock"...'
-  updates[] = '<referenceBlock name="someBlock">...'  
-```
-- addUpdate(string) - string XML from file
-
-
-## Demonstrate the ability to customize the Magento UI using themes. 
-
-### When would you create a new theme?
-
-- create new theme from scratch without parent when design is very different from existing
-- inherit new theme to add smaller customizations - move, hide, reorder elements, change block arguments, html attributes
-- new theme can be assigned to specific store view, for example for b2b store
-- theme can apply dynamically based on browser user agent as exception - enter regexp in
-    _Content > Design > Implementation > [Edit] > Design Rule > User Agent Rules_
-    Full page cache and design exception:
-```
-    plugin magento-store/etc/di.xml:
-    Magento\Framework\App\Action\AbstractAction.beforeDispatch:
-    \Magento\Framework\View\DesignLoader::load
-      \Magento\Framework\App\Area::load('design')
-        \Magento\Framework\App\Area::_initDesign
-      \Magento\Framework\App\Area::detectDesign
-        \Magento\Framework\App\Area::_applyUserAgentDesignException
-        \Magento\Framework\View\DesignExceptions::getThemeByRequest
-
-    plugin \Magento\PageCache\Model\App\CacheIdentifierPlugin::afterGetValue - checks rule design exception
-    View\DesignExceptions::getThemeByRequest
-```
-
-- etc/view.xml file *doesn't merge* with parent themes, it either inherits completely from parent
-  or your theme has new version of it
-
-
-### How do you define theme hierarchy for your project?
-
-theme.xml - parent
-
-Determine theme hierarchy of existing project:
-
-- Go to _Content > Design > Configuration_
-- Check "Theme Name" column on row with store view under question
-- find paths to all available themes in app/etc/design/frontend/* or vendor/*/theme-* (conventionally)
-  or find programmatically:
-```php
-  (new \Magento\Framework\Component\ComponentRegistrar())->getPaths('theme');
-```
-- open theme path/theme.xml, check `<parent>` node and so on
-
-## Demonstrate the ability to customize/debug templates using the template fallback process.
-
-
-
-### How do you identify which exact theme file is used in different situations?
-
-
-### How can you override native files?
-
-- theme layout override module file: <theme>/layout/override/base/*.xml
-- theme layout override one of parent theme layouts: <theme>/layout/override/Magento/luma/*.xml
-- static asset for theme, e.g. <theme>/web/js/theme.js
-- static asset for module, e.g. <theme>/Magento_Checkout/web/js/view/minicart.js
-- static asset for locale:
-```
-  <theme>/web/i18n/en_US/Magento_Checkout/
-  <theme>/web/i18n/en_US/
-```
-  
diff --git a/3. Customizing the Magento UI/2. Determine how to use blocks.md b/3. Customizing the Magento UI/2. Determine how to use blocks.md
deleted file mode 100644
index 5a704a9..0000000
--- a/3. Customizing the Magento UI/2. Determine how to use blocks.md	
+++ /dev/null
@@ -1,190 +0,0 @@
-## Demonstrate an understanding of block architecture and its use in development.
-
-### [View\Element\AbstractBlock](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/View/Element/AbstractBlock.php):
-- data automatically assigns to _data, can access data arguments later, e.g. in _construct
-- `jsLayout` data argument
-- toHtml:
-  * event `view_block_abstract_to_html_before`
-  * disable module output still works
-  * if not in cache:
-    + _beforeToHtml
-    + _toHtml
-    + save cache
-  * _afterToHtml - always, even when cached
-  * event `view_block_abstract_to_html_after`
-
-### [View\Element\Template](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/View/Element/Template.php):
-- `template` data argument
-- `_viewVars` property, assign()
-- `_toHtml` renders template when defined
-  * getTemplateFile = [View\Element\Template\File\Resolver](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/View/Element/Template/File/Resolver.php)::getTemplateFileName
-  * fetchView
-    + [View\Element\Template\File\Validator](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/View/Element/Template/File/Validator.php)::isValid - checks allowed directory (view_preprocessed/module/theme) or symlink
-    + if bad file, log and throw error in DEV mode
-    + View\TemplateEnginePool::get by file extension
-      - phtml - [View\TemplateEngine\Php](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/View/TemplateEngine/Php.php) - extract vars, include file
-      - xhtml - [View\TemplateEngine\Xhtml](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/View/TemplateEngine/Xhtml.php)
-      - \Magento\Developer\Model\TemplateEngine\Decorator\DebugHints
-    + engine.render(block, template, viewVars)
-- default `getCacheKeyInfo` - store code, template, base URL. By default *store aware*
-- helper methods:
-  * getMediaDirectory
-  * getRootDirectory
-  * getObjectData
-  * getBaseUrl
-  
-admin configuration `dev/template/allow_symlink`, default false
-
-#### Which objects are accessible from the block?
-
-- $this = \Magento\Framework\View\TemplateEngine\Php
-- $this->something() is proxied to $block->something() via magic `__call` function - only public available!
-- isset($this->something) -> isset($block->something)
-- $this->property = $block->property
-- $this->helper() gets singleton of AbstractHelper
-
-#### What is the typical block’s role?
-
-As much business logic as possible should be moved out of template, and blocks provide access to processed
-data for templates. Actual data crunching can (and should) be proxied further to models.
-
-## Identify the stages in the lifecycle of a block.
-
-- block is generated
-  * builder.generateLayoutBlocks
-  * layout.generateElements
-  * readerPool.interpret - View\Layout\Reader\Block::interpret - resolves params, schedules structure element
-    + `<action ifconfig method>`
-    + `<arguments>`
-    + attributes: class, group, template, ttl, display, acl
-    + visibilityConditions: attribute `ifconfig`, attribuet `aclResource`, child `<visibilityCondition name="" className=""><arguments.../></visibilityCondition>`
-  * generatorPool.process - View\Layout\Generator\Block::process - actually creates block
-    + generate all blocks
-      `__construct`, `_construct`
-    + set layout to all blocks, event after each
-      `block.setLayout`, `block._prepareLayout`
-      event `core_layout_block_create_after`
-    + call all actions
-
-generator.generateBlock:
-- generator.createBlock -> `__construct()` -> `_construct` -> check argument 'template' -> setTemplate
-  * generator.getBlockInstance
-  * block.setType(classname)
-  * block.setNameInLayout
-  * block.addData(arguments.data)
-- block.setTemplate (when available)
-- block.setTtl (when available)
-
-### Arguments 
-
-Block arguments are treated like data-arguments. Arguments values set in a layout file
-can be accessed in templates using the get{ArgumentName}() and has{ArgumentName}() methods.
-
-Arguments values set in a layout file can be accessed in templates using the get{ArgumentName}()
-and has{ArgumentName}() methods. The latter returns a boolean defining whether there's any value set.
-{ArgumentName} is obtained from the name attribute the following way: for getting the value of
-`<argument name="some_string">` the method name is getSomeString().
-
-[Magento docs - Layout instructions](http://devdocs.magento.com/guides/v2.0/frontend-dev-guide/layouts/xml-instructions.html#argument)
-
-### Block viewModel concept
-
-Magento 2.2 suggests moving block business logic to separate viewModel classes.
-
-Avoid extending this template class, because with inheriting the template block is the constructor is very large.
-
-If you need custom presentation logic in your blocks, use this class as block, and declare
-custom view models in block arguments in layout handle file.
-
-View model parameter can have any name.
-Also, one block can have multiple view models injected via layout.
-
-Example:
-
-```xml
-<block name="my.block" class="Magento\Backend\Block\Template" template="My_Module::template.phtml" >
-     <arguments>
-         <argument name="viewModel" xsi:type="object">My\Module\ViewModel\Custom</argument>
-     </arguments>
-</block>
-```
-
-In template, access your model instead of the block:
-
-```php
-$viewModel = $block->getData('viewModel');
-// or
-$viewModel = $block->getViewModel();
-```
-
-[ViewModels in Magento 2](https://www.yireo.com/blog/1856-viewmodels-in-magento-2)
-
-
-### In what cases would you put your code in the _prepareLayout(), _beforeToHtml(), and _toHtml() methods?
-
-`_prepareLayout` - most commonly extended:
-
-At this stage all blocks in layout are generated, but _prepareLayout is only running,
-  so some blocks might still be not initialized completely.
-
-- set page config title
-
-    ```php
-    $this->pageConfig->getTitle()->set(__('Address Book'));
-    ```
-
-- edit head block, e.g. add RSS
-- add breadcrumbs
-- create new block, set as child - e.g. grid
-
-`_beforeToHtml`:
-- can't change page title?
-- some blocks are rendered, can't change them
-- assign additional template values
-- delay computation to the latest point until render. If block is not rendered we save computation
-
-`_toHtml`:
-- block without template, put custom rendering here, e.g. calling external API
-- suppress template output if should not render by condition - return empty string
-
-
-#### How would you use events fired in the abstract block?
-
-`view_block_abstract_to_html_before`:
-- edit cache params - lifetime, ttl, tags
-- add column to grid
-- edit template params - e.g. set disable edit flag
-
-`view_block_abstract_to_html_after`:
-- edit html - replace, add content, add wrappers
-
-
-## Describe how blocks are rendered and cached.
-
-toHtml, load cache, [when not in cache: _beforeToHtml, _toHtml], _afterToHtml, save cache
-
-- data attribute `cache_lifetime` must be set
-- cache key one of:
-  * data attribute `cache_key` = BLOCK_`$cache_key`
-  * default getCacheKeyInfo: [name in layout]
-  * or BLOCK_`getCacheKeyInfo()` - by default name in layout. By default *same for all stores*!
-- cache tags for automatic invalidation:
-  * data attribute `cache_tags`
-  * + implicit tag 'block_html'
-  * if instanceof DataObject\IdentityInterface, `getIdentities`
-
-## Identify the uses of different types of blocks.
-
-- View\Element\AbstractBlock - custom logic
-- View\Element\Template - any template
-- View\Element\Text - set text programmatically
-- etc.
-
-### When would you use non-template block types?
-
-Something like CMS page - admin controls block content and layout. Another example - dynamic robots.txt
-whose content is stored in DB.
-
-### In what situation should you use a template block or other block types?
-
-Use template block whenever possible to allow for theme markup customization.
diff --git a/3. Customizing the Magento UI/3. Demonstrate ability to use layout and XML schema.md b/3. Customizing the Magento UI/3. Demonstrate ability to use layout and XML schema.md
deleted file mode 100644
index 10b1a71..0000000
--- a/3. Customizing the Magento UI/3. Demonstrate ability to use layout and XML schema.md	
+++ /dev/null
@@ -1,375 +0,0 @@
-# Demonstrate ability to use layout and XML schema
-## Describe the elements of the Magento layout XML schema, including the major XML directives.
-
-### Xsi:type niceties
-
-*string*:
-
-```xml
-<argument xsi:type="string" translate="bool"></argument>
-```
-
-  - true values: [true, 1, 'true', '1']
-  - false values: [false, 0, 'false', '0']
-
-[*options*](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/View/Layout/Argument/Interpreter/Options.php):
-
-```xml
-<argument name="options" xsi:type="options" model="Magento\Tax\Model\TaxClass\Source\Customer"/>
-```
-    
-  - Model class instance of Data\OptionSourceInterface - toOptionArray.
-  - Result = model.toOptionArray, slightly processed, optgroup will probably not work.
-
-[*url*](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/View/Layout/Argument/Interpreter/Url.php):
-
-```xml
-<argument xsi:type="url" path="">
-    <param name="_current">1</param>
-</argument>
-```
-```xml
-<argument name="configuration" xsi:type="array">
-    <item name="recently_viewed_product" xsi:type="array">
-        <item name="requestConfig" xsi:type="array">
-            <item name="syncUrl" xsi:type="url" path="catalog/product/frontend_action_synchronize"/>
-        </item>
-    </item>
-</argument>
-```
-
-[*helper*](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/View/Layout/Argument/Interpreter/HelperMethod.php):
-```xml
-<action method="setTemplate">
-    <argument name="template" xsi:type="helper" helper="Magento\Paypal\Helper\Hss::getReviewButtonTemplate">
-        <param name="name">Magento_Paypal::hss/review/button.phtml</param>
-    </argument>
-</action>
-```
-
-### Major directives:
-
-*Node readers*:
-- `<html>`
-- `<head>`
-- `<body>`
-- `<move>`
-- `<container>`
-- `<block>`
-- `<uiComponent>`
-
-*Generators*:
-- `<head>`
-- `<body>`
-- `<container>`
-- `<block>`
-- `<uiComponent>`
-
-*Scheduled Structure* - View\Page\Config\Structure:
-- `scheduledPaths[$blockName] = $parent1/$parent2/$blockName`
-- `scheduledStructure[$blockName] = $row`
-- `scheduledData[$blockName] = [attributes actions arguments]`
-- `elementAttributes[element][]`
-- `removeElementAttributes[element][attribute]`
-- `assets[/original/link/src] = attributes`
-- `removeAssets[/some/src/] = /some/src`
-- `title = __('Value')`
-- `metadata[name] = content`
-- `bodyClasses[]`
-
-
-### `<HTML>` node reader [View\Page\Config\Reader\Html](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/View/Page/Config/Reader/Html.php)
-
-Html reader is used for collecting attributes of html in to the scheduled page structure.
-
-```xml
-<html>
-    <attribute name="html_attribute_name" value="html_attribute_value" />
-</html>
-```
-
-*structure*:
-
-`elementAttributes['html']['html_attribute_name'] = 'html_attribute_value'`
-
-*render*:
-
-- View\Result\Page::render
-- `'htmlAttributes' => $this->pageConfigRenderer->renderElementAttributes($config::ELEMENT_TYPE_HTML),`
-- View\Page\Config\Renderer::renderElementAttributes - join(' ', name-value pairs)
-- root.phtml
-    ```html
-    <!doctype html>
-    <html <?= /* @escapeNotVerified */ $htmlAttributes ?>>
-    ```
-
-### `<HEAD>` node reader [View\Page\Config\Reader\Head](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/View/Page/Config/Reader/Head.php)
-
-- `<css src="" ...attributes>`, `<script src="" ...attributes>`, `<link src="" ...attributes>`
-  View\Page\Config\Structure::addAssets:
-  structure `assets['path/to/src'] = attributes`
-
-- `<remove src="">`
-  structure.removeAssets:
-  structure `removeAssets['path/to/src'] = 'path/to/src'`
-
-- `<title>`
-  structure.setTitle
-  `title = __($title)`
-
-- `<meta name="" content="">` or `<meta property="" content="">`
-  structure.setMetadata:
-  `metadata[name] = content`
-
-- `<attribute name value />`
-  structure.setElementAttribute
-  `elementAttributes[head][attribute]=value`
-
-  render:
-  * View\Result\Page::render
-  * `'headAttributes' => $this->pageConfigRenderer->renderElementAttributes($config::ELEMENT_TYPE_HEAD),`
-  * root.phtml: `<head <?= /* @escapeNotVerified */ $headAttributes ?>>`  - key1=value1 key2=value2
-
-### `<HEAD>` generator [View\Page\Config\Generator\Head](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/View/Page/Config/Generator/Head.php)
-
-- processRemoveAssets - structure.`assets` vs structure.`removeAssets`
-- processRemoveElementAttributes - `elementAttributes` vs `removeElementAttributes`
-- processAssets - `assets`
-  * add *remote* assets, attribute src_type='controller' or src_type='url'
-    - example `<css src="" src_type="controller" content_type="link" />`
-    - Page\Config::addRemotePageAsset
-  * add normal assets View\Page\Config::addPageAsset
-- processTitle - copy from structure to page config
-- processMetadata - copy
-- processElementAttributes - copy: html, head etc.
-
-
-### `<BODY>` node reader [View\Page\Config\Reader\Body](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/View/Page/Config/Reader/Body.php)
-
-```xml
-<body>
-    <attribute name="id" value="html-body"/>
-    <attribute name="class" value="preview-window"/>
-</body>
-```
-
-- "class" attributes - structure.`bodyClasses[] = class-name`
-  tip: empty class clears all
-- other attributes - structure.`elementAttributes[body][attribute-name] = value`
-  * View\Result\Render `'bodyAttributes' => $this->pageConfigRenderer->renderElementAttributes($config::ELEMENT_TYPE_BODY),`
-  * root.phtml `<body ... <?= /* @escapeNotVerified */ $bodyAttributes ?>>`
-- calls readerPool to process `<body>` contents recursively
-
-### `<BODY>` generator [View\Page\Config\Generator\Body](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/View/Page/Config/Generator/Body.php)
-
-Copies structure.`bodyClasses[]` to View\Page\Config::addBodyClass
-- adds to pageConfig.`elements[body][class] = '...'`
-
-### `<MOVE>` node reader [View\Layout\Reader\Move](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/View/Layout/Reader/Move.php)
-
-```xml
-<move element='' destination='' as='' (after=''|before='') />
-```
-
-structure.`scheduledMoves[elementName] = [destination, siblingName, isAfter, alias]`
-
-All moves are processed in View\Layout\GeneratorPool before all other generators:
-- generatorPool.buildStructure
-  * scheduleElement - creates array structure `_elements`
-    - `_elements[parentId]['children'][childId] = alias`
-    - `_elements[childId]['parent'][parentId] = alias`
-    - bad relations `brokenParent[elementId] = 1`
-  * reorderElements
-  * moveElementInStructure -- here
-  * removeElement - broken parents
-  * remove elements when 'visibilityConditions' doesn't match
-
-### `<CONTAINER>`, `<REFERENCECONTAINER>` node reader [View\Layout\Reader\Container](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/View/Layout/Reader/Container.php)
-
-- `<container>`:
-  * `<container name as before/after>` - schedule structure
-    structure.`scheduledStructure[name] = [container alias parent sibling is_after]`
-  * containerReader.mergeContainerAttributes
-    structure.`scheduledData[name][attributes] = [tag id class label display]`
-
-- `<referenceContainer name remove ...attributes>`
-  * possible to un-remove
-  * merges normal container attributes
-
-- calls readerPool to process contents recursively, just like `<body>`
-
-
-### `<BLOCK>` node reader [View\Layout\Reader\Block](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/View/Layout/Reader/Block.php)
-
-- schedules structure View\Layout\ScheduledStructure\Helper::scheduleStructure
-  * generates name if needed - like `{$parent_name}_schedule_block1`
-  * [type='block', alias='$as', parent_name='$parent', sibling_name='$beforeAfterName', is_afer=true/false]
-  * `scheduledPaths[$blockName] = $parent1/$parent2/$blockName`
-  * `scheduledStructure[$blockName] = $row`
-- data['attributes'] - [class, group, template, ttl, display, acl]
-- data['actions'][] = [method, arguments, ifconfig, scope=STORE]
-- data['arguments'] = parse `<arguments>`:
-  * `<argument name="$name">...</argument>`
-  View\Layout\Argument\Parser::parse
-  Config\Converter\Dom\Flat::convert
-
-```xml
-<arguments>
-    <argument>Text node</argument>
-    <argument>
-        <item>
-          <item>...parsed recursively</item>
-        </item>
-    </argument>
-</arguments>
-```
-
-- blockReader.evaluateArguments
-  * Data\Argument\InterpreterInterface::evaluate
-  * Data\Argument\Interpreter\Composite as layoutArgumentReaderInterpreter
-
-```xml
-<argument name="interpreters" xsi:type="array">
-    <item name="options" xsi:type="object">Magento\Framework\View\Layout\Argument\Interpreter\Options</item>
-    <item name="array" xsi:type="object">layoutArrayArgumentReaderInterpreterProxy</item>
-    <item name="boolean" xsi:type="object">Magento\Framework\Data\Argument\Interpreter\Boolean</item>
-    <item name="number" xsi:type="object">Magento\Framework\Data\Argument\Interpreter\Number</item>
-    <item name="string" xsi:type="object">Magento\Framework\Data\Argument\Interpreter\StringUtils</item>
-    <item name="null" xsi:type="object">Magento\Framework\Data\Argument\Interpreter\NullType</item>
-    <item name="object" xsi:type="object">Magento\Framework\View\Layout\Argument\Interpreter\Passthrough</item>
-    <item name="url" xsi:type="object">Magento\Framework\View\Layout\Argument\Interpreter\Passthrough</item>
-    <item name="helper" xsi:type="object">Magento\Framework\View\Layout\Argument\Interpreter\Passthrough</item>
-</argument>
-```
-
-Scheduled Structure:
-- `scheduledPaths[$blockName] = $parent1/$parent2/$blockName`
-- `scheduledStructure[$blockName] = $row`
-- `scheduledData[$blockName] = [attributes actions arguments]`
-
-
-### `<BLOCK>` generator [View\Layout\Generator\Block](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/View/Layout/Generator/Block.php)
-
-View\Layout\Generator\Block::process: - creates block instance, evaluates arguments
-- finds scheduled elements with type = 'block'
-- generator.generateBlock
-  * Data\Argument\InterpreterInterface::evaluate
-
-  View\Layout\Argument\Interpreter\Decorator\Updater as layoutArgumentGeneratorInterpreter
-    - modifies result via registered [View\Layout\Argument\UpdaterInterface](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/View/Layout/Argument/UpdaterInterface.php)
-
-```xml
-<argument name="testArrayWithUpdater" xsi:type="array">
-    <updater>Magento\Framework\View\Layout\Argument\UpdaterInterface</updater>
-    <item name="add" xsi:type="array">
-        <item name="label" xsi:type="string" translate="true">Move to Archive</item>
-        <item name="url" xsi:type="string">*/sales_archive/massAdd</item>
-    </item>
-</argument>
-<argument name="dataSource" xsi:type="object">
-    <updater>Magento\Sales\Model\Grid\CollectionUpdater</updater>
-</argument>
-```
-
-  Data\Argument\Interpreter\Composite as layoutArgumentGeneratorInterpreterInternal
-
-```xml
-<argument name="interpreters" xsi:type="array">
-    <item name="options" xsi:type="object">Magento\Framework\View\Layout\Argument\Interpreter\Options</item>
-    <item name="array" xsi:type="object">layoutArrayArgumentGeneratorInterpreterProxy</item>
-    <item name="boolean" xsi:type="object">Magento\Framework\Data\Argument\Interpreter\Boolean</item>
-    <item name="number" xsi:type="object">Magento\Framework\Data\Argument\Interpreter\Number</item>
-    <item name="string" xsi:type="object">Magento\Framework\Data\Argument\Interpreter\StringUtils</item>
-    <item name="null" xsi:type="object">Magento\Framework\Data\Argument\Interpreter\NullType</item>
-    <item name="object" xsi:type="object">layoutObjectArgumentInterpreter</item>
-    <item name="url" xsi:type="object">Magento\Framework\View\Layout\Argument\Interpreter\Url</item>
-    <item name="helper" xsi:type="object">Magento\Framework\View\Layout\Argument\Interpreter\HelperMethod</item>
-</argument>
-```
-
-- every block:
-  * block.setLayout -> _prepareLayout
-  * event `core_layout_block_create_after`
-- every scheduled action:
-  * generator.generateAction - evaluate arguments and call_user_func_array
-
-
-### `<UI_COMPONENT>` node reader [View\Layout\Reader\UiComponent](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/View/Layout/Reader/UiComponent.php)
-
-```xml
-<ui_component name group aclResource ifconfig>
-    <visibilityCondition name="" className="">
-        <arguments>...</arguments>
-    </visibilityCondition>
-</ui_component>
-```
-
-- scheduleStructure - structure.`scheduledStructure[name] = [uiComponent alias parent sibling is_after]`
-- attributes: group, component, aclResource + visibilityConditions
-  structure.`scheduledData[name] = [attributes]`
-- read ui config, merge definition
-  + _magic here_
-- ui component generated layout elements -> - calls readerPool to process contents recursively
-
-
-### `<UI_COMPONENT>` generator [View\Layout\Generator\UiComponent](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/View/Layout/Generator/UiComponent.php)
-
-- finds all scheduled elements of type uiComponent
-- generateComponent - creates components, prepares recursively, wraps in layout block
-  * View\Element\UiComponentFactory::create - View\Element\UiComponentInterface compatible with BlockInterface
-  * prepare component and its children recursively - UiComponent.prepare - providers, buttons, form data etc.
-  * creates layout block wrapper for component - \Magento\Ui\Component\Wrapper\UiComponent - just renders component
-
-
-### How do you use layout XML directives in your customizations?
-- move elements
-- referenceContainer - change attributes, add children
-- referenceBlock - change template, position before/after, add arguments, add children, set no display
-- add HEAD scripts/styles
-
-## Describe how to create a new layout XML file.
-
-- Place layout in one of directories:
-  * custom-module/view/base/layout/
-  * custom-module/view/frontend/layout/
-  * custom-theme/Magento_Checkout/layout/
-
-  Or the same with page_layout directory.
-
-- When extending page layout, don't copy-paste layout="..." attribute if not intended.
-- Use standard XML namespaces:
-
-```xml
-<layout xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-  xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/layout_generic.xsd">
-```
-```xml
-<page
-  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-  xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd"
->
-```
-
-## Describe how to pass variables from layout to block.
-
-- use block arguments:
-
-```xml
-<block class="Magento\Customer\Block\Account\Navigation" name="top.links">
-    <arguments>
-        <argument name="css_class" xsi:type="string">header links</argument>
-    </arguments>
-</block>
-```
-
-[Magento docs](http://devdocs.magento.com/guides/v2.0/frontend-dev-guide/layouts/xml-instructions.html#argument)
-
-- substitute dynamic argument value as result of helper execution
-
-```xml
-<action method="setTemplate">
-    <argument name="template" xsi:type="helper" helper="Magento\Paypal\Helper\Hss::getReviewButtonTemplate">
-        <param name="name">Magento_Paypal::hss/review/button.phtml</param>
-    </argument>
-</action>
-```
diff --git a/3. Customizing the Magento UI/4. Utilize JavaScript in Magento.md b/3. Customizing the Magento UI/4. Utilize JavaScript in Magento.md
deleted file mode 100644
index d71a833..0000000
--- a/3. Customizing the Magento UI/4. Utilize JavaScript in Magento.md	
+++ /dev/null
@@ -1,465 +0,0 @@
-# Utilize JavaScript in Magento
-## Describe different types and uses of JavaScript modules. Which JavaScript modules are suited for which tasks?
-
-- plain requirejs module
-
-    Good for executing regular JS code, maybe some legacy code that doesn't require active interactions
-    with other existing JS components on the page.
-
-    ```html
-    <script type="text/x-magento-init">
-    {
-        "*": {
-            "mage/cookies": {
-                "expires": null,
-                "path": "/",
-                "domain": ".m22ee.local",
-                "secure": false,
-                "lifetime": "3600"
-            }
-        }
-    }
-    </script>
-    ```
-    Element selector syntax is good for passing container element, so module can bind event listeners only
-    within given element instead of querying DOM directly. Makes code tidier.
-
-    ```html
-    <script type="text/x-magento-init">
-    {
-        "[data-gallery-role=gallery-placeholder]": {
-            "mage/gallery/gallery": {
-                "mixins":["magnifier/magnify"],
-                "magnifierOpts": {"fullscreenzoom":"20","top":"","left":"","width":"","height":"","eventType":"hover","enabled":"false"},
-                "data": [/*...*/],
-                "options": {
-                    // ...
-                },
-                "fullscreen": {
-                    // ...
-                },
-                "breakpoints": {"mobile":{"conditions":{"max-width":"767px"},"options":{"options":{"nav":"dots"}}}}            }
-        }
-    }
-    </script>
-   ```
-
-- action - set some data, call AJAX
-  * Magento_Checkout/js/action/select-payment-method.js
-  * Magento_Customer/js/action/login.js - when called, calls AJAX, when done executes callbacks and adds messages
-
-- shared model for data access - ko.observable properties
-  * Magento_Customer/js/model/customer
-  * Magento_Checkout/js/model/quote
-  * some state - is loading etc. Magento_Checkout/js/model/shipping-address/form-popup-state.js
-  * validation rules Magento_Ui/js/lib/validation/rules.js
-
-- view - ui component
-  * form Magento_Ui/js/form/form
-  * grid Magento_Ui/js/grid/listing
-  * minicart Magento_Checkout/js/view/minicart
-
-- jQuery widget
-
-  ```JS
-  {
-    $.widget('mage.shippingCart', {
-      ... // this.config, this.element
-    })
-    return $.mage.shippingCart;
-  }
-  $(element).shippingCart(...)
-  ```
-
-
-## Describe UI components.
-
-Base class hierarchy:
-
-- uiClass
-- uiElement + uiEvents + links
-- uiCollection
-
-### *uiClass* - Magento_Ui/js/lib/core/class
-
-[About the uiClass library](http://devdocs.magento.com/guides/v2.2/ui_comp_guide/concepts/ui_comp_uiclass_concept.html)
-
-The uiClass is an abstract class from which all components are extended. The uiClass is
-a low-level class and is rarely used as direct parent for UI components’ classes.
-
-Adds support for extending classes `extend()` and calling parent methods `_super()`.
-
-methods:
-- initialize, initConfig
-
-properties:
-- contructor.defaults
-
-
-### *uiElement* - Magento_Ui/js/lib/core/element/element.js
-
-[About the uiElement class](http://devdocs.magento.com/guides/v2.2/ui_comp_guide/concepts/ui_comp_uielement_concept.html)
-
-Powers most of UI components internals. Adds support for features:
-- automatic data linking between models
-- automatic module loading
-- working with observable properties
-- stateful properties - stored automatically
-- events - on/off/trigger
-
-methods:
-- initialize, initObservable, initModules
-properties:
-- tracks, modules, source, provider, 
-
-initLinks:
-- imports
-- exports
-- links == same value in imports and exports
-
-```
-imports: {
-    totalRecords: '${ $.provider }:data.totalRecords'
-}
-```
-same as
-```
-imports: {
-    totalRecords: 'example.example_data_source:data.totalRecords'
-}
-```
-
-```
-exports: {'visible': '${ $.provider }:visibility'}
-imports: {'visible': '${ $.provider }:visibility'}
-links: {'visible': '${ $.provider }:visibility'}
-links: {value: '${ $.provider }:${ $.dataScope }'}
-```
-
-```
-listens: {'${ $.namespace }.${ $.namespace }:responseData': 'setParsed'}
-listens: {'${ $.provider }:data.overload': 'overload reset validate'} -- call multiple callbacks
-listens:
-  'index=create_category:responseData' => 'setParsed',
-  'newOption' => 'toggleOptionSelected'
-```
-
-$.someProperty - property of the UI component in the scope of this component
-
-conditions in string literals:
-
-'${ $.provider }:${ $.customScope ? $.customScope + "." : ""}data.validate': 'validate'
-
-
-### initObservable
-- observe([{Boolean} isTracked,] {String|Array|Object} listOfProperties)
-- observe('var1 var2 var3')
-- observe(['var1', 'var2', 'var3'])
-- observe(true, 'var1 var2 var3') -- isTracked, use property accessors
-- observe(false, 'var1 var2 var3') -- not tracked, use observable properties
-- observe({var1: 'value', var2: true}) -- initial values from object
-
-### initModules
-```JS
-defaults: {
-    modules: {
-        '%myProperty%': '%linkToTheComponent%',
-        externalSource: '${ $.externalProvider }',
-        street: '${ $.parentName }.street',
-        city: '${ $.parentName }.city',
-        country: '${ $.parentName }.country_id',
-        productForm: 'product_form.product_form'
-    }
-}
-```
-
-
-
-## uiCollection - Magento_Ui/js/lib/core/collection.js
-
-[About the uiCollection class](http://devdocs.magento.com/guides/v2.2/ui_comp_guide/concepts/ui_comp_uicollection_concept.html)
-
-Enables components to have nested child components:
-- `elems` observable property
-- initElement
-- getChild, insertChild, removeChild, destroyChildren
-- regions
-
-
-## Module_Ui/js/core/app, uiLayout - Module_Ui/js/core/renderer/layout
-
-[The uiLayout service object](http://devdocs.magento.com/guides/v2.2/ui_comp_guide/concepts/ui_comp_uilayout_concept.html)
-
-Renders UI collection components structure, instantiates classes, sets children etc.
-
-- app -> layout()
-- run
-- iterator
-- process
-- addChild - current node to parent
-- manipulate - appendTo, prependTo, insertTo
-- initComponent
-    * loadDeps
-    * loadSource (source='uiComponent')
-    * initComponent
-      + long async -> global function var component = new Constr(_.omit(node, 'children'));
-
-
-## In which situation would you use UiComponent versus a regular JavaScript module?
-
-[Overview of UI components](http://devdocs.magento.com/guides/v2.2/ui_comp_guide/bk-ui_comps.html)
-
-UI components work well together: they communicate with each other via the uiRegistry service that
-tracks their asynchronous initialization.
-
-Therefore, if we need to extend something that has already been implemented as a hierarchy
-of UI components or add a new feature that should interact with other UI components,
-it’s easier and more effective to use a UI component.
-
-
-## Describe the use of requirejs-config.js, x-magento-init, and data-mage-init.
-
-### requirejs-config.js
-
-We are interested in:
-- map as alias - same as defining virtual type preference in DI
-```js
-var config = {
-    map: {
-        '*': {
-            'Magento_Swatches/js/swatch-renderer' : 'Custom_Module/js/swatch-renderer'
-        }
-    }
-};
-```
-- map as preference - same as preference in DI, replace one class with another
-```js
-var config = {
-    map: {
-        '*': {
-            uiElement:      'Magento_Ui/js/lib/core/element/element',
-        }
-    }
-};
-```
-- mixins - same as around plugins in DI. This is Magento customization over requireJS
-```js
-var config = {
-    config: {
-        mixins: {
-            'Magento_Checkout/js/action/place-order': {
-                'Magento_CheckoutAgreements/js/model/place-order-mixin': true
-            }
-        }
-    }
-};
-```
-
-Use `wrapper` model to implement around functionality for functions.
-
-Place order mixin body:
-```
-define([
-    'jquery',
-    'mage/utils/wrapper',
-    'Magento_CheckoutAgreements/js/model/agreements-assigner'
-], function ($, wrapper, agreementsAssigner) {
-    'use strict';
-
-    return function (placeOrderAction) {
-
-        /** Override default place order action and add agreement_ids to request */
-        return wrapper.wrap(placeOrderAction, function (originalAction, paymentData, messageContainer) {
-            agreementsAssigner(paymentData);
-
-            return originalAction(paymentData, messageContainer);
-        });
-    };
-});
-
-```
-
-Plain requirejs objects can be extended directly.
-
-Example - mixin over Magento_Checkout/js/model/quote:
-
-```
-define([
-    'jquery',
-    'ko'
-], function($, ko) {
-    'use strict';
-
-    var checkoutMethod = ko.observable(null);
-
-    return function(quote) {
-        return $.extend(quote, {
-            checkoutMethod: checkoutMethod
-        });
-    };
-});
-```
-
-### Text/x-magento-init and Data-mage-init
-
-[Alan Storm - Javascript Init Scripts](http://alanstorm.com/magento_2_javascript_init_scripts)
-
-Following 3 snippets are completely equivalent:
-```html
-<div class="selector" data-mage-init="{'Custom_Module/js/something': {option1: 'value1', option2: 'value2'}}"></div>
-```
-
-```html
-<div class="selector"></div>
-<script type="text/x-magento-init">
-{
-  '.selector': {
-    'Custom_Module/js/something': {
-       option1: 'value1',
-       option2: 'value2'
-    }
-  }
-}
-</script>
-```
-
-```html
-<div class="selector"></div>
-<script>
-require(['Custom_Module/js/something'], function(fn) {
-    fn({option1: 'value1', option2: 'value2'}, DOMElement('.selector'));
-});
-</script>
-```
-
-
-How Magento executes scripts:
-- mage/bootstrap.js
-- lib/web/mage/apply/scripts.js
-  * parses init scripts `document.querySelectorall('script[type="text/x-magento-init"]')`
-  * converts to data-attribute format on according element, e.g. `<div data-mage-init="...">`
-  * scripts with `*` selector (virtuals, no node to assign to) are collected separately
-- mage/apply/main.js
-  * parses data-attribute init scripts `document.querySelectorAll('[data-mage-init]')` - including converted `<script type="text/x-magento-init">`
-  * merges virtuals from above (`*` selector)
-  * creates components from parsed definitions
-
-In other words:
-- we return component-function
-- magento gets it via require and invokes with arguments. E.g. uiComponent(config, node)
-- node '*' -> false
-- selector matching multiple nodes - multiple module instances (like jQuery plugin)
-
-Benefits:
-- top-level selector is defined outside js module
-- initial values from server are defined outside modules
-
-Example:
-```html
-<div class="selector-one" data-mage-init="{'Custom_Module/js/something': {option1:'', option2:''}}"></div>
-<div id="selector-two"></div>
-
-<script type="text/x-magento-init">
-{
-  '#selector-two': {
-    'Custom_Module/js/component': {
-       mixins: [],
-       option1: value1,
-       option2: value2
-    }
-  }
-}
-</script>
-
-<script type="text/x-magento-init">
-{
-    "*": {
-        "Magento_Ui/js/core/app": {
-            "components": {
-                "customer": {
-                    "component": "Magento_Customer/js/view/customer"
-                }
-            }
-        }
-    }
-}
-</script>
-```
-
-Transforms into following:
-```html
-<div class="selector-one" data-mage-init="{'Custom_Module/js/something': {option1:'', option2:''}}"></div>
-<div id="selector-two" data-mage-init="{'Custom_Module/js/component': {mixins: [], option1: value1, option2: value2}}"></div>
-<script>
-// somewhere in closures...
-virtuals[] = {
-  el: false,
-  data: '{"Magento_Ui/js/core/app": {"components": {"customer": {"component": "Magento_Customer/js/view/customer"}}}}'
-}
-<script>
-
-```
-
-And then JS is executed like this:
-```JS
-require(['Custom_Module/js/something'], function(fn) {
-  // your component should return function-constructor with 2 params: (config, $element)
-  fn({option1:'', option2:''}, DOMElement('.selector-one'));
-});
-require(['Custom_Module/js/something'], function(fn) {
-  fn({option1: value1, option2: value2}, DOMElement('#selector-two'));
-});
-require(['Magento_Ui/js/core/app'], function(appFn) {
-  // element = false when selector '*'
-  appFn({"components": {"customer": {"component": "Magento_Customer/js/view/customer"}}}, false);
-})
-```
-
-There's interesting possibility to return jQuery widget instead of contructor function.
-Magento detects this and calls widget accordingly.
-
-Here's how:
-```js
-require([component], function (fn) {
-    if (typeof fn === 'object') {
-        fn = fn[component].bind(fn);
-    }
-
-    if (_.isFunction(fn)) {
-        fn(config, el);
-    } else if ($(el)[component]) {
-        $(el)[component](config);
-    }
-});
-```
-
-
-### Mixins example
-
-```HTML
-<script type="text/x-magento-init">
-    {
-        "[data-gallery-role=gallery-placeholder]": {
-            "mage/gallery/gallery": {
-                "mixins":["magnifier/magnify"],
-                "magnifierOpts": ...,
-                "data": ...,
-                "options": ...
-            }
-        }
-    }
-</script>
-```
-
-```JS
-element = $('[data-gallery-role=gallery-placeholder]');
-config = {magnifierOpts:..., data:..., options:...}
-
-require(['mage/gallery/gallery'], function(gallery) {
-  require(["magnifier/magnify"], function(magnify) {
-    var result = magnify(config, element); // call for each mixin. Magnify will use config.magnifierOpts
-    extend(config, result); // magnify returns same config, config not changed
-  })
-  gallery(config, element);
-});
-```
diff --git a/3.Magento-Customising-The-UI.md b/3.Magento-Customising-The-UI.md
new file mode 100755
index 0000000..16691d6
--- /dev/null
+++ b/3.Magento-Customising-The-UI.md
@@ -0,0 +1,618 @@
+3 - Customizing the Magento UI
+==================================
+
+3.1 Demonstrate ability to utilize themes and the template structure
+--------------------------------------------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**Demonstrate the ability to customize the Magento UI using themes.**
+
+![Magento Section Chevron](./images/icon-chevron.png)Theme directory
+
+app/design/frontend/Vendor/themename/
+```
+- composer.json
+- registration.php
+- theme.xml - name, parent, logo
+- etc/view.xml - currently catalog images configuration
+- i18n/
+- media/ - pub logo here
+- Magento_Checkout/ - extend specific module
+---- layout/ - normally layouts are extended
+------- override/base/ - special case: completely replace base layout for module
+------- override/theme/Magento/luma/ - special case: completely replace specific theme layout
+---- templates/ - replace module files
+---- web/ - replace module files
+- web/ - replace theme files
+---- js/
+---- css/
+------- source/
+---- fonts/
+---- images/
+---- i18n/en_US/ - locale-specific file replacement (without module)
+---- i18n/en_US/Magento_Checkout/ - locale-specific module file replacement
+```
+
+![Magento Exam Information](./images/icon-info.png)In multiple choice if you are presented with something around theme structure you should know the basic structure having worked with this daily
+
+![Magento Section Chevron](./images/icon-chevron.png)Layout
+
+> You can customise layouts / templates / html / css & js by placing overrides in the theme directory.
+>
+> Normally layouts are merged, extending parent ones.
+>
+> Full override
+>
+> To completely replace original module layout file, e.g. to replace vendor/magento/module-checkout/view/frontend/layout/default.xml, place new file in Magento_Checkout/layout/override/base/default.xml
+
+| Theme layout | Override |
+| --- | --- |
+| Base `vendor/magento/module-checkout/view/frontend/layout/default.xml` | `<theme_dir>/Magento_Checkout/layout/override/base/default.xml` |
+| Luma (parent theme) `vendor/magento/theme-frontend-luma/Magento_Checkout/layout/default.xml` | `<theme_dir>/Magento_Checkout/layout/override/Magento/luma/default.xml` |
+
+![Magento Exam Information](./images/icon-info.png)I'm personally not aware of this "override trick" / placing into the override directory within the teme to completely override a layout so this could be worth learning. In case this isn't true however, a quick answer would be to say that you can override module/vendor files by placing them in the theme.
+
+![Magento Exam Information](./images/icon-info.png)It is not possible to use the "override trick" inside a module, only in theme. You cannot create a new module app/code/MyVendor/MyModule/view/frontend/layout/override/... and replace layout files for example.
+
+![Magento Section Chevron](./images/icon-chevron.png)Locale
+
+> You can replace static files with locale-specific - JS, logo, font etc. You have 2 places:
+
+*   Non-module specific, e.g. theme asset - `<theme_dir>web/i18n/en_US/`
+*   From some module - `<Namespace>/<Module>/web/i18n/en_US/Magento_Checkout/`
+
+![Magento Exam Question](./images/icon-question.png)**How is the theme loaded?**
+
+> Module Magento_Store is responsible for loading themes in it's etc/di.xml file. Theme is loaded during [Dependency Injection](#h.9ofwnl5q9fnf) (DI) compilation. Detailed process include:
+```
+App\Action\AbstractAction.beforeDispatch
+
+App\Area::_initDesign
+
+get/setDesignTheme = theme
+
+get/setArea = frontend
+
+getLocale
+
+getConfigurationDesignTheme - Load config "design/theme/theme_id"
+
+setDefaultDesignTheme - area, theme model, is. loads theme model from DB
+```
+
+> The theme is set via the admin in the ‘design/theme/theme_id' configuration.
+
+![Magento Section Chevron](./images/icon-chevron.png)Theme types
+
+Physical themes
+> Physical refers to the fact that those themes are defined by files. For example, the blank and luma theme are physically defined under app/design/frontend/
+
+Virtual themes
+> This is yet unclear but I think virtual themes refer to themes you can create in the backend which extends existing physical themes but it seems like it's not fully implemented yet. Unused.
+
+Staging
+> Something to do with EE campaigns. Unused in CE.
+
+![Magento Exam Question](./images/icon-question.png)**When would you create a new theme?**
+
+*   When you want to edit the look of your storefront you can create one:
+    *   From scratch, if your design is totally different to default.
+    *   Inherited from a parent (blank / luma) to add smaller customizations - move, hide, reorder elements, change block arguments, html attributes.
+*   Theme can apply dynamically based on browser user agent as an exception - enter regexp in Content > Design > Implementation > [Edit] > Design Rule > User Agent Rules Full page cache and design exception.
+
+![Magento Exam Question](./images/icon-question.png)**How do you define theme hierarchy for your project?**
+```
+<theme_dir>/theme.xml:
+
+<parent> tag
+```
+
+![Magento Exam Question](./images/icon-question.png)**Demonstrate the ability to customize/debug templates using the template fallback process. How do you identify which exact theme file is used in different situations?**
+
+> The first step in customizing a template is to locate it. This is done by either:
+
+* finding the path in layout XML, using the debugger,
+* Or by enabling template hints (`bin/magento dev:template-hints:enable`).
+* Another way is to find a unique string in the HTML (translation, tag or class). Searching the entire project directory often yields the location of the file. Be aware that there are not only `.phtml` templates, but also `.html` knockout.js templates or `.xhtml` template files.
+    * Once you find the file, create a folder in your theme for the module that you copied it from. For example, if you are modifying a template from the `Magento_Catalog` module, create a `Magento_Catalog` folder inside your theme directory.
+
+
+![Magento Exam Question](./images/icon-question.png)**How can you override native files?**
+
+File Override Fallback Rule
+
+| Path example | Priority order | Type |
+| --- | --- | --- |
+| `layout/override/base/*.xml` | 1b | Theme module e.g. `app/design/frontend/Vendor/themename/Magento_Checkout` |
+| `layout/override/Magento/luma/*.xml` | 1a - This will override base for all themes inherited from luma | Theme module e.g. app/design/frontend/Vendor/themename/Magento_Checkout |
+| `<theme_dir>/Magento_Checkout/web/js/view/minicart.js` | 2b | Static asset for module within theme |
+| `<theme_dir>/web/i18n/en_US/Magento_Checkout/` | 2a - if you create a locale then all stores deployed with en_US will prioritise this | Static asset for specific locale within theme |
+
+![Magento Exam Information](./images/icon-info.png)Again is this "override trick" - may need to confirm this is still in use.
+
+3.2 Determine how to use blocks
+-------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**Demonstrate an understanding of block architecture and its use in development.**
+
+![Magento Section Chevron](./images/icon-chevron.png)Blocks
+
+> Blocks satisfy the [ViewModel part of MVVM architecture](#h.i0qq8aqgijv7). Blocks are PHP classes that provide data for template files (.phtml) and implement rendering. Also, blocks can cache the results of template rendering. All block classes extend the Magento\Framework\View\Element\AbstractBlock abstract class which implements Magento\Framework\View\Element\BlockInterface and provides the following functionality:
+
+*   Data automatically assigns to _data, can access data arguments later, e.g. in `_construct`
+*   `jsLayout` data argument
+*   Render - `toHtml`
+    *   Event view_block_abstract_to_html_before is dispatched.
+    *   Disable module output still works.
+    *   If not in cache: `_beforeToHtml`, `_toHtml`, save cache
+    *   `_afterToHtml` - always, even when cached
+*   Event: `view_block_abstract_to_html_after`
+
+![Magento Section Chevron](./images/icon-chevron.png)Templates
+
+> Template files are responsible for loading the template file (.phtml) they inherit the class  Magento\Framework\View\Element\Template which is an extension of the Magento\Framework\View\Element\AbstractBlock class from above. Specifically this class is responsible for:
+
+*   Template data arguments
+*   `_viewVars` property, assign()
+*   `_toHtml` renders template when defined
+    *   `getTemplateFile` = `Magento\Framework\View\Element\Template\File\Resolver::getTemplateFileName`
+    `fetchView`
+    *   `Magento\Framework\View\Element\Template\File\Validator::isValid` - checks allowed directory (view_preprocessed/module/theme) or symlink
+    *   If its a bad file, log and throw error in DEV mode
+    *   `Magento\Framework\View\TemplateEnginePool::get()` - by file extension phtml, xhtml.
+    *   `Magento\Developer\Model\TemplateEngine\Decorator\DebugHints`
+    *   engine.render(block, template, viewVars)
+*   default getCacheKeyInfo - store code, template, base URL.
+
+![Magento Exam Information](./images/icon-info.png)FYI: Admin configuration `dev/template/allow_symlink`, default = false [following an exploit](https://maxchadwick.xyz/blog/what-allow-symlinks-actually-does&sa=D&ust=1609223264702000&usg=AOvVaw05eFXzMZwapN_T8Hm98fHU).
+
+![Magento Exam Information](./images/icon-info.png)Just remember: Blocks are PHP classes that provide data for template files (.phtml) and implement rendering. Also, blocks can cache the results of template rendering.
+
+![Magento Exam Question](./images/icon-question.png)**Which objects are accessible from the block?**
+
+Within a template file (.phtml) the following objects are accessible:
+
+*   `$this` - Instance of class `Magento\Framework\View\TemplateEngine\Php`
+*   `$block` - Instance of the custom block class defined in layout of which is calling this template.
+*   `$this->helper()` - Gets the singleton class of AbstractHelper which calls upon the Object Manager to generate other Object Instances this template may need access to.
+
+![Magento Exam Information](./images/icon-info.png)`$this` is proxied to $block via magic __call function so $this->property = $block->property
+
+![Magento Exam Note Warning](images/icon-warning.png)Using `$this` & `$this->helper()` [considered an anti-pattern & is now deprecated](https://magento.stackexchange.com/questions/325189/is-it-okay-to-use-this-helper-in-phtml-files&sa=D&ust=1609223264703000&usg=AOvVaw1gTPUq_b4GUeO4NjTu-Vdj). `$block` should be used in its place
+
+![Magento Exam Question](./images/icon-question.png)**What is the typical block's role?**
+
+> Blocks satisfy the [ViewModel part of MVVM architecture](#h.i0qq8aqgijv7). As much business logic as possible should be moved out of template, and blocks provide access to processed data for templates. Actual data crunching can (and should) be proxied further to Models.
+
+![Magento Exam Information](./images/icon-info.png)Blocks can be thought of as data containers for a template, which represents a piece of the HTML on the page. In layouts XML, you can manage blocks on page and add new ones, set templates to move and delete.
+
+![Magento Exam Question](./images/icon-question.png)**Identify the stages in the lifecycle of a block.**
+
+The block life cycle consists of two phases:
+
+1.  Generating blocks:
+    *  `Magento\Framework\View\Page\Config::publicBuild()`
+    *  `Magento\Framework\View\Page\Config::build()`
+    *  `Magento\Framework\View\Layout\Builder::build()`
+    *  `Magento\Framework\View\Layout\Builder::generateLayoutBlocks()`
+    *  `Magento\Framework\View\Layout::generateElements()`
+    *  `Magento\Framework\View\Layout\GeneratorPool::process()`
+    *  GeneratePool - goes through all generators and generates all scheduled elements. It has generators with the following elements:
+        *  `Magento\Framework\View\Page\Config\Generator\Head`
+        *  `Magento\Framework\View\Page\Config\Generator\Body`
+        *  `Magento\Framework\View\Layout\Generator\Block`
+        *  `Magento\Framework\View\Layout\Generator\Container`
+        *  `Magento\Framework\View\Layout\Generator\UiComponent`
+
+2.  Rendering blocks:
+    *  `Magento\Framework\View\Result/Page::render()`
+    *  `Magento\Framework\View\Layout::getOutput()`
+
+> Blocks are instantiated at the moment the layout is created. They are not executed at that time, just instantiated. Also during this phase, the structure is built, the children of blocks are set, and for each block, the prepareLayout() method is called. However, rendering occurs in the later rendering phase.
+
+![Magento Exam Information](./images/icon-info.png)Just remember: Blocks are generated, then rendered - that is the main 2 stages in its life lifecycle.
+
+![Magento Exam Question](./images/icon-question.png)**Describe block arguments**
+
+| Attribute | Description | Values | Required
+| --- | --- | --- | --- |
+| `class` | Name of a class that implements rendering of a particular block. An object of this class is responsible for actual rendering of block output. | A fully-qualified class name, such as Vendor\Module\Block\Class. Defaults to Magento\Framework\View\Element\Template. | No |
+| `name` | Name that can be used to address the block to which this attribute is assigned. The name must be unique per generated page. If not specified, an automatic name will be assigned in the format ANONYMOUS_n | | 0-9, A-Z, a-z, underscore (_), period (.), dash (-). Should start with a letter. Case-sensitive. | No |
+| `before` | Used to position the block before an element under the same parent. The element name or alias name is specified in the value. Use dash (-) to position the block before all other elements of its level of nesting. See [](https://devdocs.magento.com/guides/v2.3/frontend-dev-guide/layouts/xml-instructions.html%23fedg_xml-instrux_before-after&sa=D&ust=1609223264710000&usg=AOvVaw2vzXxub4ZE1fZ6x1aB2o2W) [before and after attributes](https://devdocs.magento.com/guides/v2.3/frontend-dev-guide/layouts/xml-instructions.html%23fedg_xml-instrux_before-after&sa=D&ust=1609223264711000&usg=AOvVaw10SW-i3aOGPkEKkgi21z_z) for details. | Element name or dash (-) | No |
+| `after` | Used to position the block after an element under the same parent. The element name or alias name is specified in the value. Use dash (-) to position the block after all other elements of its level of nesting. See [](https://devdocs.magento.com/guides/v2.3/frontend-dev-guide/layouts/xml-instructions.html%23fedg_xml-instrux_before-after&sa=D&ust=1609223264712000&usg=AOvVaw0_MSqb4TUWSfxLWn8bnHCi) [before and after attributes](https://devdocs.magento.com/guides/v2.3/frontend-dev-guide/layouts/xml-instructions.html%23fedg_xml-instrux_before-after&sa=D&ust=1609223264712000&usg=AOvVaw0_MSqb4TUWSfxLWn8bnHCi) for details. | Element name or dash (-) | No |
+| `template` | A template that represents the functionality of the block to which this attribute is assigned. `Vendor_Module::path/to/template.phtml` (Scope is already in the templates directory of the module) | No |
+| `as` | An alias name that serves as identifier in the scope of the parent element | 0-9, A-Z, a-z, underscore (_), period (.), dash (-). Case-sensitive. | No |
+| `cacheable` | Defines whether a block element is cacheable. This can be used for development purposes and to make needed elements of the page dynamic. ![Magento Exam Note Warning](images/icon-warning.png)This attribute renders the whole page uncached. | true or false | No |
+| `ifconfig` | Makes the block's visibility dependent on a system configuration field | XPath to the system configuration field. E.g. contact/contact/enabled | No |
+
+Example:
+```xml
+<block name="my.block" class="Magento\Backend\Block\Template" template="My_Module::template.phtml" >
+    <arguments>
+        <argument name="viewModel" xsi:type="object">My\Module\ViewModel\Custom</argument>
+    </arguments>
+</block>
+```
+
+![Magento Exam Question](./images/icon-question.png)**In what cases would you put your code in the _prepareLayout(), _beforeToHtml(), and _toHtml() methods?**
+
+![Magento Section Chevron](./images/icon-chevron.png)`_prepareLayout()`
+
+Most commonly used in adminhtml
+
+*   Set page config title
+*   Edit head block, e.g. add RSS
+*   Add breadcrumbs
+*   Create new block, set as child - e.g. grid
+
+![Magento Section Chevron](./images/icon-chevron.png)`_beforeToHtml()`
+
+*   Adding extra child blocks
+*   Assign additional template values to block
+*   Delay computation to the latest point until render. If  is not rendered we save computation
+
+![Magento Section Chevron](./images/icon-chevron.png)`_toHtml()`
+
+Using this method, you can manipulate block rendering, complement the condition, make wrappers for html , change the template for the block, block without template, put custom rendering here, suppress template output if should not render by condition such as returning an empty string.
+
+![Magento Exam Question](./images/icon-question.png)**How would you use events fired in the abstract block?**
+
+![Magento Section Chevron](./images/icon-chevron.png)`view_block_abstract_to_html_before`:
+
+*   Edit cache params - lifetime, ttl, tags
+*   Add column to grid
+*   Edit template params - e.g. set disable edit flag
+
+![Magento Section Chevron](./images/icon-chevron.png)`view_block_abstract_to_html_after`:
+
+*   Edit html - replace, add content, add wrappers
+
+![Magento Exam Question](./images/icon-question.png)**Describe how blocks are rendered and cached.**
+
+> The most important method for rendering a block is `Magento\Framework\View\Element\AbstractBlock::toHtml()`.
+>
+> First, it runs _loadCache(), and if the cache is missing, then it runs `_beforeToHtml()` after the block is rendered by the method `_toHtml()`. Afterward, the cache is saved `_saveCache($html)` and run `_afterToHtml($html)`.
+
+![Magento Exam Information](./images/icon-info.png)Remember all blocks have a `Magento\Framework\View\Element\AbstractBlock::toHtml()` In which cache is called/created.
+
+> Method `_loadCache()` uses cache_key return by `getCacheKey()` and `_saveCache($html)` – cache_tags obtained by the method `getCacheTags()`. Cache_key each block is added up like:
+>
+> `BLOCK_CLASS::CACHE_KEY_PREFIX . $cache_key` ,
+>
+> If this property is not defined, create it:
+>
+> `BLOCK_CLASS::CACHE_KEY_PREFIX . sha1(implode('|', $this->getCacheKeyInfo()))`
+>
+> Cache_tags is an array and consists of a property `$cache_tags`, if it is defined in block and if the block instance of `Magento\Framework\DataObject\IdentityInterface` values returned by the method `getIdentities()` are added to the array. We can manage `$cache_lifetime` variable. Value will be in seconds, if you want to disable cache, you can set value to `0` or not set the value at all, because all blocks are non-cacheable by default.
+
+![Magento Exam Question](./images/icon-question.png)**Identify the uses of different types of blocks.**
+
+| Block | Class | Description |
+| --- | --- | --- |
+| Abstract Block | `Magento\Framework\View\Element\AbstractBlock` | Block without template. Parent block for all custom blocks. Your custom block would extend this. |
+| Template | `Magento\Framework\View\Element\Template` | Block with template |
+| Text | `Magento\Framework\View\Element\Text` | Just rendering text |
+| Form Key | `Magento\Framework\View\Element\FormKey` | Return hidden input with form key |
+| Message | `Magento\Framework\View\Element\Messages` | Rendering notification message by type |
+
+![Magento Exam Question](./images/icon-question.png)**When would you use non-template block types?**
+
+> Applying non-template block types is wise when we use simple renderers. Another reason for using such block types is when block content is dynamically generated or stored in a database or in containers. An Edge Sides Includes (ESI) block for something like GeoIP Redirect might be an example here.
+
+![Magento Exam Information](./images/icon-info.png)Something like CMS page - admin controls block content and layout. Another example - dynamic robots.txt whose content is stored in DB.
+
+![Magento Exam Question](./images/icon-question.png)**In what situation should you use a template block or other block types?**
+
+> Use template block whenever possible to allow for theme markup customization.
+
+3.3 Demonstrate ability to use layout and XML schema
+----------------------------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**Describe the elements of the Magento layout XML schema, including the major XML directives.**
+
+| Directive | Description |
+| --- | --- |
+| `<html>` | Html reader is used for collecting attributes of html in to the scheduled page structure. |
+| `<head>` | Sets the HTML DOM head property |
+| `<body>` | Sets the HTML DOM body property |
+| `<move>` | Move allows changing elements' order and parent. All moves are processed in View\Layout\GeneratorPool before all other generators.You can move either a container or a block. |
+| `<container>` | Containers represent the placeholders within that web page structure I.e the wireframe and automatically render it's children |
+| `<block>` | `View\Layout\Generator\Block::process`: - creates block instance, evaluates arguments. Blocks represent the UI controls or components within the container placeholders. Does not automatically render it's children |
+| `<uiComponent>` | Magento UI components are used to represent distinct UI elements, such as tables, buttons, dialogs, and others such as Knockout JS components. [See example here about how this is laid out in an XML Layout.](https://devdocs.magento.com/guides/v2.3/ui_comp_guide/bk-ui_comps.html%23ui-component-used-in-the-frontend-design-area&sa=D&ust=1609223264732000&usg=AOvVaw0HFsDsU9yTt4xlajgamTns) They are designed for simple and flexible user interface (UI) rendering. Components are responsible for rendering result page fragments and providing/supporting further interactions of JavaScript components and servers. |
+
+![Magento Exam Information](./images/icon-info.png)The purpose of a page layout is to create a structured, common set of layout instructions to render pages. Most pages on a website can be categorized as fitting into a 1, 2, or 3-column container system. These page layouts can be selected in the admin panel to provide a specific layout per page. Look at a vendor copy of [checkout_index_index.xml](https://github.com/magento/magento2/blob/2.3/app/code/Magento/Checkout/view/frontend/layout/checkout_index_index.xml&sa=D&ust=1609223264733000&usg=AOvVaw3bttzFkzTA5SUapsscd1sP) if you want a nice overview of how such a file is laid out.
+
+![Magento Exam Question](./images/icon-question.png)**How do you use layout XML directives in your customizations?**
+
+*   `<move>` - Move elements
+*   `<referenceContainer>` - change attributes, add children
+*   `<referenceBlock>` - change template, position before/after, add arguments, add children, set no display
+*   `<head>` - Add HEAD scripts/styles
+
+![Magento Exam Question](./images/icon-question.png)**Describe how to create a new layout XML file.**
+
+![Magento Section Chevron](./images/icon-chevron.png)Place layout in one of directories:
+
+*   `<module_dir>`/view/base/layout/
+*   `<module_dir>`/view/frontend/layout/
+*   `<theme_dir>`/Magento_Checkout/layout/
+
+![Magento Exam Information](./images/icon-info.png)When extending page layout, don't copy-paste layout="..." attribute if not intended.
+
+![Magento Section Chevron](./images/icon-chevron.png)Use standard XML namespaces
+```xml
+<?xml version="1.0"?>
+<layout xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/layout_generic.xsd">
+
+ ...
+
+</layout>
+```
+```xml
+<?xml version="1.0"?>
+<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
+   ...
+</page>
+```
+
+![Magento Exam Question](./images/icon-question.png)**Describe how to pass variables from layout to block.**
+
+![Magento Section Chevron](./images/icon-chevron.png)Block arguments:
+```xml
+<block class="Magento\Customer\Block\Account\Navigation" name="top.links">
+   <arguments>
+       <argument name="css_class" xsi:type="string">header links</argument>
+   </arguments>
+</block>
+```
+![Magento Exam Information](./images/icon-info.png)[More in Magento DevDocs on use of block arguments](https://devdocs.magento.com/guides/v2.3/frontend-dev-guide/layouts/xml-instructions.html%23argument&sa=D&ust=1609223264738000&usg=AOvVaw3C9W6M5H3sMIX71o3XcsOG)
+
+![Magento Section Chevron](./images/icon-chevron.png)Substitute dynamic argument value as result of helper execution:
+```xml
+<action method="setTemplate">
+   <argument name="template" xsi:type="helper" helper="MY_VENDOR\MY_MODULE\Helper\Data::getStuff">
+       <param name="name">VENDOR_MODULE::path/to/template.phtml</param>
+   </argument>
+</action>
+```
+![Magento Exam Information](./images/icon-info.png)I didn't know this! [Magento DevDocs on use of helper params](https://devdocs.magento.com/guides/v2.3/frontend-dev-guide/layouts/xml-instructions.html%23argument&sa=D&ust=1609223264740000&usg=AOvVaw3VC8ljhpCLd1XlwFgmh44Q) The helper can use only public methods. In this example the getReviewButtonTemplate() method should be public. The argument with helper type can contain param items which can be passed as a helper method parameters.
+
+3.4 Utilize JavaScript in Magento
+---------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**Describe different types and uses of JavaScript modules.**
+
+![Magento Section Chevron](./images/icon-chevron.png)A "Plain RequireJS" module:
+```html
+<script type="text/x-magento-init">
+{
+   "*": {
+       "mage/cookies": {
+           "expires": null,
+           "path": "/",
+           "domain": ".my.domain.local",
+           "secure": false,
+           "lifetime": "3600"
+       }
+   }
+}
+</script>
+```
+![Magento Exam Information](./images/icon-info.png)Good for executing regular JS code, maybe some legacy code that doesn't require active interactions with other existing JS components on the page.
+
+![Magento Section Chevron](./images/icon-chevron.png)An "Element Selector" requirejs module:
+```html
+<script type="text/x-magento-init">
+{
+   "[data-gallery-role=gallery-placeholder]": {
+       "mage/gallery/gallery": {
+           "mixins":["magnifier/magnify"],
+           "magnifierOpts": {"fullscreenzoom":"20","top":"","left":"","width":"","height":"","eventType":"hover","enabled":"false"},
+           "data": [/*...*/],
+           "options": {
+               // ...
+           },
+           "fullscreen": {
+               // ...
+           },
+           "breakpoints": {"mobile":{"conditions":{"max-width":"767px"},"options":{"options":{"nav":"dots"}}}}            }
+   }
+}
+</script>
+```
+![Magento Exam Information](./images/icon-info.png)Element selector syntax is good for passing container element, so a module can bind event listeners only on a given element instead of querying DOM directly. Makes code tidier.
+
+![Magento Section Chevron](./images/icon-chevron.png)An "Action" module:
+
+*   `Magento_Checkout/js/action/select-payment-method`
+*   `Magento_Customer/js/action/login` - when called, calls AJAX, when done executes callbacks and adds messages
+
+![Magento Exam Information](./images/icon-info.png)Set some data, call AJAX
+
+![Magento Section Chevron](./images/icon-chevron.png)A "Shared Model" in a module, e.g.
+
+*   `Magento_Customer/js/model/customer`
+*   `Magento_Checkout/js/model/quote`
+*   Some state - is loading etc.
+*   `Magento_Checkout/js/model/shipping-address/form-popup-state` validation rules `Magento_Ui/js/lib/validation/rules`
+
+![Magento Exam Information](./images/icon-info.png)Shared model for data access - ko.observable properties
+
+![Magento Section Chevron](./images/icon-chevron.png)View - UI Component, e.g.
+
+*   Forms - `Magento_Ui/js/form/form`
+*   Grid - `Magento_Ui/js/grid/listing`
+*   Minicart - `Magento_Checkout/js/view/minicart`
+
+![Magento Section Chevron](./images/icon-chevron.png)Finally, a jQuery widget:
+```js
+{
+    .widget('mage.shippingCart', {
+        ... // this.config, this.element
+    })
+    return $.mage.shippingCart;
+}
+$(element).shippingCart(...)
+```
+![Magento Exam Question](./images/icon-question.png)**Which JavaScript modules are suited for which tasks?**
+
+*   Plain RequireJS - Supplying functionality to all elements e.g. including standard JS or 3rd party library
+*   Element Selector - For applying contained functionality within the scope of an element.
+*   Shared Model - For data access & using ko.observable properties
+*   Action - AJAX Requests, when done executes callbacks and adds messages
+*   View - UI Component - Forms, Minicart, Grid
+*   jQuery widget - Modals, Accordion, Pop-ups
+
+![Magento Exam Question](./images/icon-question.png)**Describe UI components?**
+
+> Magento UI components are used to represent distinct UI elements, such as tables, buttons, dialogs, and others.
+>
+> They are designed for simple and flexible user interface (UI) rendering. Components are responsible for rendering result page fragments and providing/supporting further interactions of JavaScript components and servers.
+>
+> Magento UI components are implemented as a standard module named [Magento_UI](https://devdocs.magento.com/guides/v2.3/mrg/ce/Ui.html&sa=D&ust=1609223264748000&usg=AOvVaw3ffMUMWMVTAqn41vsS8vxc).
+
+![Magento Section Chevron](./images/icon-chevron.png)`uiClass`
+
+The `uiClass` is an abstract class from which all components are extended. It's low-level and is rarely used as direct parent for UI components' classes.
+
+
+![Magento Section Chevron](./images/icon-chevron.png)`uiElement` + `uiEvents` + `links`
+
+A direct successor of the uiClass library. When creating a new component, use the `uiElement` class as a direct parent, if your component will be the last in the components hierarchy chain.
+
+Methods available
+
+*   initialize
+*   initObservable
+*   initModules
+
+Properties available
+
+*   tracks
+*   modules
+*   source
+*   provider
+
+![Magento Section Chevron](./images/icon-chevron.png)`uiElement`
+
+> UI Elements establish data links between other models via the "defaults" property, automatic data linking between models, working with observable & stateful properties and events (on/off/trigger) with uiEvents.
+
+Example of a data link:
+```json
+{
+    "defaults": {
+        "imports": {
+            "visible": "${ $.provider }:visibility"
+        },
+        "exports": {
+            "items": "checkout.sidebar.summary.cart_items:items"
+        },
+        "links": {
+            "visible": "${ $.provider }:visibility"
+        }
+    }
+}
+```
+
+Example of using links in a component's configuration .xml file:
+
+```xml
+<argument name="data" xsi:type="array">
+    <item name="config" xsi:type="array">
+        <item name="links" xsi:type="array">
+            <item name="visible" xsi:type="string">sample_config.sample_provider:visibility</item>
+        </item>
+    </item>
+</argument>
+```
+
+![Magento Exam Information](./images/icon-info.png)`uiElement` is the main class you usually inherit from. Just remember that `uiElement`'s make use of the "defaults" property which can be used in XML. Possesses observable & stateful properties and events of UIEvent class.
+
+
+
+![Magento Section Chevron](./images/icon-chevron.png)`uiCollection`
+
+The `uiCollection` library class should be used as a base class by any components that contain a collection of child UI components. `uiCollection` inherits from the `uiElement` class.
+
+Notable Methods:
+
+*   `getChild`
+*   `insertChild`
+*   `removeChild`
+*   `destroyChildren`
+*   `destroy`
+*   `remove`
+*   `initElement`
+
+Notable Properties:
+
+*   `elems`
+*   `regions`
+
+![Magento Exam Information](./images/icon-info.png)`elems` - Enables components to have nested child components
+
+![Magento Exam Information](./images/icon-info.png)Essentially `uiCollection` is an array of uiElement's
+
+![Magento Section Chevron](./images/icon-chevron.png)`uiLayout`
+
+JavaScript function object used for initializing and configuring UI components.
+
+Notable methods:
+
+*   The `run()` method is the class entry point represented by uiLayout and has the following signature:
+
+`uiLayout` Notable properties:
+
+| Property | Type | Description |
+| --- | --- | --- |
+| `name` | String | Name of the component. |
+| `parent` | String | Full name of the component's parent element. |
+| `template` | String | Path to the component's .html template. |
+| `config` | Object | Configuration properties for the UI component. |
+| `children` | Object | Configuration nodes for children components. |
+| `isTemplate` | Boolean | Whether to save the configuration as a template. |
+| `nodeTemplate` | String | The full name of a saved configuration template. |
+| `provider` | String | The full name of the DataSource UI component. This property is inherited from the parent if skipped. |
+
+![Magento Exam Information](./images/icon-info.png)uiLayout would be used to programmatically add new layouts to the uiRegistry. Good in the situation where you might be dynamically creating layouts.
+
+![Magento Exam Question](./images/icon-question.png)**In which situation would you use UiComponent versus a regular JavaScript module?**
+
+*   When wanting to create Magento UI components that represent distinct UI elements, such as tables, buttons, dialogs, and others.
+*   UI components work well together: they communicate with each other via the `uiRegistry` (service that tracks their asynchronous initialization).
+*   Extending something that has already been implemented as a hierarchy of UI components or adding a new feature that should interact with other UI components.
+
+![Magento Exam Information](./images/icon-info.png)Probably very important to know!
+
+![Magento Exam Question](./images/icon-question.png)**Describe the use of requirejs-config.js, x-magento-init, and data-mage-init.**
+
+![Magento Section Chevron](./images/icon-chevron.png)requirejs-config.js
+
+[map as alias](https://devdocs.magento.com/guides/v2.3/javascript-dev-guide/javascript/requirejs.html%23requirejs-config-map&sa=D&ust=1609223264770000&usg=AOvVaw0NvsZ5OZdZigpO3YTD2Wwu) - same as defining virtual type [Preference in DI](#h.9ofwnl5q9fnf)
+[map as preference](https://devdocs.magento.com/guides/v2.3/javascript-dev-guide/javascript/custom_js.html%23js_replace&sa=D&ust=1609223264771000&usg=AOvVaw0LO9SubTYlre9LQF4pX05h) - same as [Preference in DI](#h.9ofwnl5q9fnf), replace one class with another
+[mixins](https://devdocs.magento.com/guides/v2.3/javascript-dev-guide/javascript/js_mixins.html%23example&sa=D&ust=1609223264771000&usg=AOvVaw3x_iq9sXJSrvSjQbncUy3L) - same as around [Plugins Interceptors in DI](#h.nc1ow1wmf2km). This is Magento customization over requireJS
+
+![Magento Exam Information](./images/icon-info.png)requirejs-config.js is essentially the di.xml of JS UiComponents
+
+![Magento Section Chevron](./images/icon-chevron.png)x-magento-init & data-mage-init
+
+*   Javascript Init Methods provide a way to invoke a stand alone [RequireJS module](#h.h647tzfdps5a) (defined with define) as a program.
+*   It discourages directly embedding JavaScript into a page.
+*   They provide a way to pass that program a server side generated JSON object.
+*   They provide a way to tell that program which (if any) DOM nodes it should operate on.
+
+`x-magento-init` is the most basic way a RequireJS module can be initialised. Accepting only JSON such like:
+```html
+<script type="text/x-magento-init">
+   {
+       "*": {
+           "MyVendor_MyModule/example":{}
+       }
+   }
+</script>
+```
+data-mage-init is another way to invoke similar functionality on a specific DOM node, and that's with the data-mage-init attribute:
+```html
+<div data-mage-init='{"MyVendor_MyModule/example": {"another":"example"}}'>
+    A single div
+</div>
+```
\ No newline at end of file
diff --git a/4. Working with Databases in Magento/1. Demonstrate ability to use data-related classes.md b/4. Working with Databases in Magento/1. Demonstrate ability to use data-related classes.md
deleted file mode 100644
index 3593d32..0000000
--- a/4. Working with Databases in Magento/1. Demonstrate ability to use data-related classes.md	
+++ /dev/null
@@ -1,127 +0,0 @@
-# Demonstrate ability to use data-related classes
-
-## Describe repositories and data API classes.
-
-[Magento - Searching with Repositories](http://devdocs.magento.com/guides/v2.2/extension-dev-guide/searching-with-repositories.html)
-
-Magento 2.2 changed repository getList approach. Before you applied filters, sorts and pagination manually
-right in the `getList` method itself.
-
-Magento 2.2 takes this boilerplate routine off developer's shoulders. Just call `collectionProcessor.process()`.
-
-[Api\SearchCriteria\CollectionProcessorInterface](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/Api/SearchCriteria/CollectionProcessorInterface.php)
-[Api\SearchCriteria\CollectionProcessor](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/Api/SearchCriteria/CollectionProcessor.php)
-- this is a composite and default preference
-
-Default collection processors - always applied:
-- [FilterProcessor](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/Api/SearchCriteria/CollectionProcessor/FilterProcessor.php#L45):
-  * DI configurable *custom filters* by field name. E.g. store_id
-  * *field mapping*
-  * addFilterGroupToCollection when no custom filter defined - like before
-- [SortingProcessor](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/Api/SearchCriteria/CollectionProcessor/SortingProcessor.php#L45):
-  * DI configurable *default orders*
-  * *field mapping*
-- [PaginationProcessor](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/Api/SearchCriteria/CollectionProcessor/PaginationProcessor.php):
-  * setCurPage, setPageSize
-
-Additional processors - add them via DI for your EAV repository:
-- EAV [FilterProcessor](https://github.com/magento/magento2/blob/2.2-develop/app/code/Magento/Eav/Model/Api/SearchCriteria/CollectionProcessor/FilterProcessor.php#L45)
-  * same as normal filter processor, slightly different condition apply
-  * *field mapping*
-  * *custom filters*
-- [JoinProcessor](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/Api/SearchCriteria/CollectionProcessor/JoinProcessor.php) - used only in tax rule repository
-
-For EAV, inject virtual collection processor `Magento\Eav\Model\Api\SearchCriteria\CollectionProcessor`
-
-## How do you obtain an object or set of objects from the database using a repository?
-
-*Loading single object*
-
-While model->load() is deprecated, your repository is the place to work with resource model.
-- create empty model object with factory
-- call `resourceModel.load($object)` just like `model->load()` would.
-
-Example:
-```xml
-public function getById($blockId)
-{
-    $block = $this->blockFactory->create();
-    $this->resource->load($block, $blockId);
-    if (!$block->getId()) {
-        throw new NoSuchEntityException(__('CMS Block with id "%1" does not exist.', $blockId));
-    }
-    return $block;
-}
-```
-
-
-## How do you configure and create a SearchCriteria instance using the builder?
-
-- Api\SearchCriteriaBuilder
-- Api\SearchCriteria
-
-To build a searchCriteria object, use $searchCriteriaBuilder. You don't need a factory, this type is declared as `shared="false"`. Once `create()` method is caled, its data empties.
-
-
-## How do you use Data/Api classes?
-
-Api/:
-- repository interfaces
-- put operational interfaces - helpers etc. business logic API
-- implementation lies in models
-- usually available via WebAPI
-
-Api/Data - entity container interfaces, usually extend AbstractSimpleObject
-
-In your repository, you should return data interfaces. Some models directly implement data interfaces (catalog product), while others are completely separate - there's customer model and customer data object.
-
-Example of converting collection models to data objects in customer repository:
-```xml
-$customers = [];
-/** @var \Magento\Customer\Model\Customer $customerModel */
-foreach ($collection as $customerModel) {
-    $customers[] = $customerModel->getDataModel();
-}
-$searchResults->setItems($customers);
-```
-
-`getDataModel` is not a standard method, you implement it yourself.
-
-```xml
-public function getDataModel()
-{
-    // ...
-    $customerDataObject = $this->customerDataFactory->create();
-    $this->dataObjectHelper->populateWithArray(
-        $customerDataObject,
-        $customerData, // $customer->getData()
-        \Magento\Customer\Api\Data\CustomerInterface::class
-    );
-    // ...
-    return $customerDataObject;
-}
-```
-
-## populateWithArray helper
-
-Based on interface, calls all SETTERS with given data to fill data object
-
-[Api\DataObjectHelper::populateWithArray](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/Api/DataObjectHelper.php#L80)
-- calls data object SETTERS `set*`, `setIs*` with given raw data
-- handles `custom_attributes` - data object.setCustomAttribute
-
-
-## buildOutputDataArray
-
-Based on given interface, calls all GETTERS to make resulting data array.
-
-[Reflection\DataObjectProcessor::buildOutputDataArray](https://github.com/magento/magento2/blob/2.2-develop/lib/internal/Magento/Framework/Reflection/DataObjectProcessor.php#L72):
-- \Magento\Framework\Reflection\MethodsMap::getMethodsMap - method name and getter return types
-- filter only getters: is..., has..., get...
-- get data using interface getter, e.g. $object->getSku() - based on Interface definition
-- deduce field name by getter name, e.g. 'sku'
-- process custom_attributes \Magento\Framework\Reflection\CustomAttributesProcessor::buildOutputDataArray
-- process extension_attributes \Magento\Framework\Reflection\ExtensionAttributesProcessor::buildOutputDataArray
-- process return object: build return value objects with their return type annotation
-- process return array: cast each element to type, e.g. int[] => (int) each value
-- cast element to type
diff --git a/4.Magento-Working-With-Databases.md b/4.Magento-Working-With-Databases.md
new file mode 100755
index 0000000..660cf5d
--- /dev/null
+++ b/4.Magento-Working-With-Databases.md
@@ -0,0 +1,981 @@
+4 - Working with Databases in Magento
+=====================================
+
+4.1 Demonstrate ability to use data-related classes
+---------------------------------------------------
+
+> Repositories can be applied for working with Collections in Magento 2. It realises the Repository pattern that allows it to work with collections and entities regardless of their storage place (storing or caching are the implementation of details).
+>
+> A Repository should be stateless after instantiation. This means that every method call should not rely on previous calls nor should it affect later method calls. Any field contained in the repository class must also be stateless.
+
+![Magento Exam Question](./images/icon-question.png)**What mechanisms are available to extend existing classes, for example by adding a new attribute, a new field in the database, or a new related entity?**
+
+*   Custom EAV-Attributes - More info below
+*   Extension Attributes - More info below
+*   Declarative Schema - More info below
+*   Declarative Data - More info below
+*   Schema Patches - More info below
+*   Data Patches - More info below
+*   Custom Repositories and API Classes - More info below
+
+![Magento Exam Question](./images/icon-question.png)**Describe Repositories and data API classes.**
+
+> Repositories give service requesters the ability to perform create, read, update, and delete (CRUD) operations on entities or a list of entities. A repository is an example of a [service contract](https://devdocs.magento.com/guides/v2.2/extension-dev-guide/service-contracts/design-patterns.html&sa=D&ust=1609223264777000&usg=AOvVaw1W0IBLhVtdLevoBCn-pXDX), and its implementation is part of the [domain layer](https://devdocs.magento.com/guides/v2.3/architecture/archi_perspectives/domain_layer.html&sa=D&ust=1609223264778000&usg=AOvVaw36Pi0TnWV7_9eOsx8vcB9l).
+>
+> Repositories open your entity for the Magento 2 REST API (also requires data model interfaces).
+>
+> Repositories usually lie within the `<module_dir>/Api/` & `<module_dir>/Api/Data/` Directories.
+
+![Magento Exam Question](./images/icon-question.png)**How do you obtain an object or set of objects from the database using a repository?**
+
+In Magento 2, five basic repository functions are realized using Resource Models. They are
+
+*   `save($entity)`
+*   `getById($id)`
+*   `getList(SearchCriteria $searchCriteria)`
+*   `delete($entity)`
+*   `deleteById($id)`
+
+![Magento Exam Note Warning](images/icon-warning.png)You used to be able to save using model->save() - but this is now deprecated, your Resource Model is the place to work with data storage.
+
+![Magento Exam Question](./images/icon-question.png)**How do you configure and create a SearchCriteria instance using the builder? Describe how to filter, sort, and specify the selected values for collections and repositories.**
+
+A Search Criteria is an implementation of the [SearchCriteriaInterface class](https://github.com/magento/magento2/blob/2.2/lib/internal/Magento/Framework/Api/SearchCriteriaInterface.php&sa=D&ust=1609223264781000&usg=AOvVaw2grCpVdTjMrz79L1pEePCH) that allows you to build custom requests with different conditions. Repositories use this class to retrieve entities based on a matching criteria.
+
+![Magento Section Chevron](./images/icon-chevron.png) Filter
+
+> The Filter class is the smallest part of a Search Criteria. It allows you to add a custom field, value, and condition type to the criteria. Example of how to define a Filter:
+
+```php
+$filter
+   ->setField("url")
+   ->setValue("%magento.com")
+   ->setConditionType("like");
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)Filter Group
+
+> A collection of Filters that apply one or more criteria to a search. Example:
+
+```php
+$filter1
+   ->setField("url")
+   ->setValue("%magento.com")
+   ->setConditionType("like");
+
+$filter2
+   ->setField("store_id")
+   ->setValue("1")
+   ->setConditionType("eq");
+
+$filterGroup1->setFilters([$filter1, $filter2]);
+
+$filter3
+   ->setField("url_type")
+   ->setValue(1)
+   ->setConditionType("eq");
+
+$filterGroup2->setFilters([$filter3]);
+
+$searchCriteria->setFilterGroups([$filterGroup1, $filterGroup2]);
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)Sorting
+
+> The example below defines a Sort Order object that will sort the customer email in ascending order:
+
+```php
+$sortOrder
+   ->setField("email")
+   ->setDirection("ASC");
+
+$searchCriteria->setSortOrders([$sortOrder]);
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)Pagination
+
+> The setPageSize function paginates the Search Criteria by limiting the amount of entities it retrieves:
+
+```php
+$searchCriteria->setPageSize(20); //retrieve 20 or less entities
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)Search Result
+
+> The getList(SearchCriteria $searchCriteria) method defined in your repository should return a Search Result object. This object is an instance of a class that implements the interface [SearchResultsInterface](https://github.com/magento/magento2/blob/2.2/lib/internal/Magento/Framework/Api/SearchResultsInterface.php&sa=D&ust=1609223264787000&usg=AOvVaw0IMC3MEGEPbw8kXlNd6Y6N).
+
+![Magento Exam Question](./images/icon-question.png)**How do you use Data/Api classes?**
+
+> Api in Magento 2 is commonly used to describe Repository interfaces, further implemented by  Models and Data Models. Repository API interfaces can be applied for WebAPI requests (when they are described in `webapi.xml`). Api directory is located in modules roots, similarly to etc, Model and other directories.
+>
+> Unlike Api, `Api/Data` directory contains interfaces for the data, for example, store data or customer data.
+>
+> An excellent example for explaining the difference between Api and `Api/Data` is the implementation of `Magento\Catalog\Api\ProductRepositoryInterface` and `Magento\Catalog\Api\Data\ProductInterface`.
+>
+> ProductRepository implements a get method that loads a Product object (using ProductFactory) that implements ProductInterface for working with data.
+
+![Magento Exam Information](./images/icon-info.png)Just remember: API Interfaces where Service Contract / Repositories are kept which keep in mind WebAPI - Concerned only with how to retrieve information of a specific entity/model. `Magento\Catalog\Api\ProductRepositoryInterface` for example has methods `get()` and `save()` . API/Data on the other hand are a set of interfaces specifically for the data (which will be implemented by a Model class). `Magento\Catalog\Api\Data\ProductInterface` has model related methods like `getSku()`
+
+![Magento Exam Question](./images/icon-question.png)**Describe how to create and register new entities.**
+
+In Magento 2, entities are unique objects that contain a number of various attributes and/or parameters. Products, Orders & Customers for example. Entities are subsets of [Entity-Attribute-Values (EAV).](https://blog.magestore.com/entity-attribute-value-in-magento/&sa=D&ust=1609223264790000&usg=AOvVaw0Haxczn-QByjK23DXB7e6l)
+
+![Magento Exam Information](./images/icon-info.png)Think EAV, think catalog_product_entity ➞ eav_attribute table ➞ (`catalog_product_entity_varchar`, `catalog_product_decimal`) etc
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Step 1 - Create A Model
+
+Create a new [Module](#h.8r6t4fakpxnh) with [registration](#h.i0qq8aqgijv7), entities can only be created within a module.
+
+The Model usually lies within the `<module_dir>/Model` directory and is the sole entity class. Models are where your main business logic should be handled and is a single instance of an object. The Model will use the Resource Model to talk to the database and get/set data for The Resource Model to `save()` and `load()` / `get()`. Models will extend the class `Magento\Framework\Model\AbstractExtensibleModel`.
+
+Example Model Concrete Class:
+```php
+<?php
+
+namespace Vendor\MyModule\Model;
+class ExampleModel extends Magento\Framework\Model\AbstractExtensibleModel implements Vendor\MyModule\Api\Data\ExampleModelInterface
+{
+   /** {@inheritdoc} */
+   protected function _construct()
+   {
+       $this->_init(ResourceModel\ExampleResourceModel::class);
+   }
+
+   /** {@inheritdoc} */
+   public function getId(): int
+   {
+       return (int) $this->getData(ExampleModelInterface::ENTITY_COLUMN_TABLE_ID);
+   }
+
+   /** {@inheritdoc} */
+   public function getEntityId(): int
+   {
+       return $this->getId();
+   }
+
+   /** {@inheritdoc} */
+   public function getResource(): AbstractDb
+   {
+       return $this->_getResource();
+   }
+}
+```
+### ![Magento Section Chevron](./images/icon-chevron.png)Step 2 - Create Resource Model
+
+> Map an object to one or more database rows. A Resource Model is responsible for performing functions such as:
+
+*   Executing all CRUD (create, read, update, delete) requests. The resource model contains the SQL code for completing these requests.
+*   Performing additional business logic. For example, a resource model could perform data validation, start processes before or after data is saved, or perform other database operations.
+
+> Resource models usually lie in the `<module_dir>/Model/ResourceModel` directory. It extends the `Magento\Framework\Model\ResourceModel\Db\AbstractDb` class which handles most C.R.U.D methods. You just need to specify the "table" and "entity_id" within the Magento `_construct()` method:
+```php
+<?php
+namespace Vendor\MyModule\Model\ResourceModel;
+class ExampleResourceModel extends Magento\Framework\Model\ResourceModel\Db\AbstractDb
+{
+        protected function _construct()
+        {
+                $this->_init('my_table', 'entity_id');
+        }
+}
+```
+![Magento Exam Information](./images/icon-info.png)Resource Models and Repositories are very alike, but Resource Model represents a lower level persistence mechanism that should be used by Repositories. It is the only recommended persistence mechanism by Magento right now. Repositories are more concerned with creating access to your custom entity via the REST API.
+
+![Magento Exam Information](./images/icon-info.png)Magento uses an [active record pattern strategy for persistence](https://devdocs.magento.com/guides/v2.3/architecture/archi_perspectives/persist_layer.html&sa=D&ust=1609223264794000&usg=AOvVaw3iHooG-vMX_8WIs2944qx3). Resource Models are an important part of this pattern. Just Remember CRUD here.
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Step 3 - Create Collection
+
+> Collections encapsulate sets of models and related functionality, such as filtering, sorting, and pagination. Collections usually reside in `<module_dir>\Model\ResourceModel\ExampleModel\Collection`
+>
+> The collection extends `Magento\Framework\Model\ResourceModel\Db\Collection\AbstractCollection` - which provide
+>
+> you MySQL-like commands as methods, Popular examples methods are:
+
+*   `getConnection()`
+*   `getSelect()`
+*   `setPageSize()`
+*   `addAttributeToSelect()`
+*   `getMainTable()`
+*   `addFieldToSelect()`
+*   `addFieldToFilter()`
+*   `join()`
+
+> Collections are great if you're working with entities that have a lot of attributes, filters, or possibly a future large dataset, a good practice for debugging would be to use SQL logging to record actual SQL queries hitting the database.
+>
+> Example Collection:
+```php
+<?php
+namespace Vendor\MyModule\Model\ResourceModel\ExampleModel;
+class Collection extends Magento\Framework\Model\ResourceModel\Db\Collection\AbstractCollection
+{
+        protected function _construct()
+        {
+                $this->_init(Vendor\MyModule\Model\ExampleModel, Vendor\MyModule\Model\ResourceModel\ExampleModel);
+        }
+}
+```
+![Magento Exam Information](./images/icon-info.png)Remember that Collections are a good use for filtering, sorting, and pagination. They are not 100% necessary when creating new entities but are recommended for scalability.
+
+![Magento Exam Information](./images/icon-info.png)Collections can help us spot possible performance bottlenecks and react on time, either by adding more limiting values to setPageSize or addAttributeToSelect, or both.
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Step 4 - Schema / Data Installation & Upgrade
+
+> Declarative setup
+>
+> Declarative setup is based on database structure declarations. Schema files declare what the database structure should be, and Magento determines the differences between the current table structure and what it should be. These differences can be represented with atomic SQL operations.
+>
+> Declarative Schema is defined in [<module_dir>/etc/db_schema.xml](https://devdocs.magento.com/guides/v2.3/extension-dev-guide/declarative-schema/db-schema.html&sa=D&ust=1609223264799000&usg=AOvVaw3DX2NFuBBuc4PtRaiH0XE-)
+>
+> More on Declarative Setup in [Section 4.2](#h.8i0etxv2dw9i)
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Step 5 - Create A Repository
+
+> Repositories adhere to Magento 2 Service Contracts defined by data interfaces (but extensible by third-party modules). Repositories are a form of Service Contract keep in mind the WebAPI and is located in the <module_dir>/Api & <module_dir>/Api/Data directories then implemented in <module_dir>/Model & <module_dir>/Model/Data. Create a Interfaces in:
+
+*   `<module_dir>/Api/ExampleRepositoryInterface` - containing all the necessary Resource Model CRUD operations.
+*   `<module_dir>/Api/Data/ExampleModelInterface` - containing all the necessary getter / setter methods for your Data model.
+*   `<module_dir>/Api/DataExampleModelSearchResultInterface` - which extends the `Magento\Framework\Api\SearchResultsInterface` where you can add specific search.
+
+Implementing your Repository as a concrete class:
+```php
+<?php
+
+namespace Vendor\MyModule\Model;
+
+class ExampleRepository implements Vendor\MyModule\Api\ExampleRepositoryInterface
+{
+    public function __construct(
+        MY\MODULE\Api\Data\ExampleModelFactory $exampleFactory,
+        MY\MODULE\Model\ResourceModel\ExampleModel\CollectionFactory $exampleCollectionFactory,
+        MY\MODULE\Api\DataExampleModelSearchResultInterfaceFactory $exampleSearchResultInterfaceFactory,
+        Magento\Framework\Api\SearchCriteria\CollectionProcessorInterface $collectionProcessor
+    ) {
+        $this->exampleFactory = $exampleFactory;
+        $this->exampleCollectionFactory = $exampleCollectionFactory;
+        $this->searchResultFactory = $exampleSearchResultInterfaceFactory;
+        $this->collectionProcessor = $collectionProcessor;
+    }
+    public function getById($id)
+    {
+        $example = $this->exampleFactory->create();
+        $example->getResource()->load($example, $id);
+        if (!$example->getId()) {
+            throw new NoSuchEntityException(__('Unable to find example with ID "%1"', $id));
+        }
+        return $example;
+    }
+    public function save(MY\MODULE\Api\Data\ExampleModelInterface $example)
+    {
+        $example->getResource()->save($example);
+        return $example;
+    }
+    public function delete(MY\MODULE\Api\Data\ExampleModelInterface $example)
+    {
+        $example->getResource()->delete($example);
+    }
+    public function getList(Magento\Framework\Api\SearchCriteriaInterface $searchCriteria)
+    {
+        $collection = $this->collectionFactory->create();
+        $this->collectionProcessor->process($searchCriteria, $collection);
+        $searchResults = $this->searchResultFactory->create();
+        $searchResults->setSearchCriteria($searchCriteria);
+        $searchResults->setItems($collection->getItems());
+        return $searchResults;
+    }
+}
+
+```
+![Magento Exam Information](./images/icon-info.png)For smaller operations like getById() & save() The repository will obtain the Resource Model directly to carry out database operations.
+
+![Magento Exam Information](./images/icon-info.png)As good practice, More complex methods such as getList() in the Repository will talk to the Collection which will use the Resource Model to filter and retrieve data from the database more efficiently.
+
+![Magento Exam Information](./images/icon-info.png)Factory classes are used when creating new instantiations of the Model, more on this in the next subsection.
+
+> We must tell Magento 2 to implement these interfaces by setting a preference in the your modules `di.xml`
+```xml
+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
+    <preference for="<MY>\<MODULE>\Api\ExampleRepositoryInterface" type=" <MY>\<MODULE>\Model\ExampleRepository" />
+    <preference for="<MY>\<MODULE>\Api\Data\ExampleModelInterface" type=" <MY>\<MODULE>\Model\Example" />
+    <preference for="<MY>\<MODULE>\Api\Data\ExampleSearchResultInterface" type="Magento\Framework\Api\SearchResults" />
+</config>
+```
+
+![Magento Exam Information](./images/icon-info.png)Magento requires this definition so that when you inject Interfaces as dependencies it knows which class implementation to load. Very useful for future extension.
+
+![Magento Exam Information](./images/icon-info.png)Usually `Magento\Framework\Api\SearchResults` is nearly always a good enough implementation of `<MY>\<MODULE>\Api\Data\ExampleSearchResultInterface`.
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Step 6 - Create Factory Class
+
+> Factories are used in Object Oriented Programming as a way to instantiate an object.
+>
+> The Factory class name is the same as the Model class but with the word 'Factory' appended. Factories are injected as a dependency into other classes that you wish to use them within. During DI Compilation, it will automatically generate the Factory class in the var/generation folder if the class does not already exist. You will see the factory class in
+>
+> `var/generation/<vendor_name>/<module_name>/Model/ClassFactory.php`
+
+![Magento Exam Information](./images/icon-info.png)There is no other setup required to create Factories, Magento will generate them on `setup:di:compile`
+
+![Magento Exam Information](./images/icon-info.png)Factories are used when you want to create a new instance of a Model e.g. a new Product `Magento\Catalog\Model\Product` will be instantiated by the factory class `Magento\Catalog\Api\Data\ProductInterfaceFactory` .
+
+![Magento Exam Information](./images/icon-info.png)Think of a literal factory production line which just keeps churning out new products of the same design. Use factories to instantiate a new edition of the class.
+
+![Magento Exam Question](./images/icon-question.png)**How do you add a new table to the database?**
+
+![Magento Section Chevron](./images/icon-chevron.png)Pre-Magento 2.3  - Install Scripts
+
+Before Magento 2.3, extension developers were required to write code (PHP scripts) to change the database data / schema. The following types of scripts existed:
+
+*   [InstallSchema](https://devdocs.magento.com/videos/fundamentals/add-a-new-table-to-database/%23step-2-create-an-installschema-script&sa=D&ust=1609223264808000&usg=AOvVaw1tQ8oggkW-gSRmeG9F0RAe) / [InstallData](https://devdocs.magento.com/videos/fundamentals/add-a-new-table-to-database/%23step-3-create-an-installdata-script&sa=D&ust=1609223264809000&usg=AOvVaw0-iTq7k-aZDXDydN6iEOZn) scripts, which are executed the first time a module is installed.
+*   [UpgradeSchema](https://devdocs.magento.com/videos/fundamentals/add-a-new-table-to-database/%23step-5--create-an-upgradeschema-script&sa=D&ust=1609223264809000&usg=AOvVaw2fK09ff9UnGv__-ytpfT5W) / [UpgradeData](https://devdocs.magento.com/videos/fundamentals/add-a-new-table-to-database/%23step-6-create-the-upgradedata-script&sa=D&ust=1609223264810000&usg=AOvVaw0j9Fk1N0YdBcBqeKQbXzQj) incremental scripts, which supplement an existing module schema.
+*   [Recurring schema](https://devdocs.magento.com/guides/v2.3/extension-dev-guide/prepare/lifecycle.html%23recurring-schema-event&sa=D&ust=1609223264810000&usg=AOvVaw3XrG9_7RqUQQBBriD9p7BF) event scripts, which are executed each time you install or upgrade Magento.
+
+![Magento Exam Information](./images/icon-info.png)The main disadvantage of this approach is that Magento applies changes blindly. For example, in one version a new database column might be introduced, only to be removed in the next. Declarative setup eliminates this type of unnecessary work.
+
+![Magento Section Chevron](./images/icon-chevron.png)Post-Magento 2.3 - Declarative setup
+
+> Declarative setup is based on database structure declarations. Schema files declare what the database structure should be, and Magento determines the differences between the current table structure and what it should be. These differences can be represented with atomic SQL operations.
+>
+> Declarative Schema is defined in [<module_dir>/etc/db_schema.xml](https://devdocs.magento.com/guides/v2.3/extension-dev-guide/declarative-schema/db-schema.html&sa=D&ust=1609223264811000&usg=AOvVaw2NGT8LwDUsD4QgWZcMQjCs)
+
+![Magento Exam Question](./images/icon-question.png)**Describe the entity load and save process.**
+
+![Magento Section Chevron](./images/icon-chevron.png)Service Contracts & Repositories
+
+> The Resource Model is responsible for CRUD and Validation operations for the entity database operations including loading and saving. Magento 2's modular flexibility, however, comes at a price. Business logic tends to leak across the layers of the Magento system, which manifests as duplicated and inconsistent code. To address these issues, the Magento system introduces [Service Contracts](https://devdocs.magento.com/guides/v2.3/extension-dev-guide/service-contracts/service-contracts.html&sa=D&ust=1609223264812000&usg=AOvVaw39YIqPi26jMy3hgXfyTNw4), which hide business logic details from service requesters such as controllers, web services, and other modules under [Data Interfaces](https://devdocs.magento.com/guides/v2.3/extension-dev-guide/service-contracts/design-patterns.html%23data-interfaces&sa=D&ust=1609223264813000&usg=AOvVaw2_qDAZ5piTdHK8ci_5x_pU) AKA Repositories.
+
+![](./images/Magento-2-Certified-Professional-Developer-Guide-Request-Flow-Processing.jpg)
+
+![Magento Section Chevron](./images/icon-chevron.png)Using the Repository pattern in custom code
+
+> Repositories are designed so that we shouldn't need to inject anything else for CRUD operations in our custom modules. Products for example give you the Interface: \Magento\Catalog\Api\ProductRepositoryInterface to create products programmatically. You can tell which classes are specifically made available for custom code as they will be marked with the @api tag.
+
+As per item [8.5 of the Technical Guidelines](https://devdocs.magento.com/guides/v2.3/coding-standards/technical-guidelines.html%238-modularity&sa=D&ust=1609223264814000&usg=AOvVaw31O8OYDMRSW5GnN2CFBk7h) given by Magento:
+
+> "Only the @api code of any module can be referenced by other modules".
+>
+> We should strive to only use @api code in our custom code.
+
+![Magento Exam Question](./images/icon-question.png)**Describe how to extend existing entities.**
+
+> Schema is used to create/update DB tables and its structure. While Data is used to insert/add data into tables
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Custom (EAV) Attributes
+
+> Custom Attributes are defined as a subset of Entity-Attribute-Values (EAV). EAV attributes typically store values in several MySQL tables. For Products, a merchant can add new attributes via the admin or programmatically. For Orders & Customers this requires extending Magento programmatically.
+>
+> The Catalog module has several attributes that are defined as EAV attributes, but are treated as built-in attributes. These attributes include:
+
+*   `name`
+*   `price`
+*   `sku`
+*   etc...
+*   See the [Simple Product section below](#h.cbgifdse6zd5) for more information on how the other default attributes.
+
+> To check if an entity supports Extension Attributes, check the Api/ interface of the entity in mind for methods:
+
+*   `getCustomAttributes()`
+*   `setCustomAttributes()`
+
+> This will determine if they are available for that entity.
+>
+> You can also check if your entity extends interface `Magento\Framework\Api\CustomAttributesDataInterface` - to decipher if they are compatible with Custom (EAV) Attributes. `Magento\Framework\Api\CustomAttributesDataInterface` defines the methods that are called to get and set Custom (EAV) Attributes.
+>
+> Custom (EAV) Attributes are created using:
+
+*   [Data Patches](https://devdocs.magento.com/guides/v2.3/extension-dev-guide/declarative-schema/data-patches.html&sa=D&ust=1609223264818000&usg=AOvVaw30oojC9eaLdkq5AtiOLmpA). Using a Setup Factory e.g. Magento\Customer\Setup\CustomerSetupFactory
+*   Creating a [Service Contract](#h.i0qq8aqgijv7) which implements interface `Magento\Framework\Api\CustomAttributesDataInterface`.
+*   Declarative Schema: <module_dir>/etc/eav_attributes.xml
+
+`eav_attributes.xml` provides the EAV attributes configuration.
+
+For example, in `vendor/magento/module-catalog/etc/eav_attributes.xml` you can see many attributes like sku, status, etc and the configuration says about those attributes like if the attribute is global or it is searchable or filterable. Similar things that we do while creating a custom attribute using the Data Patch.
+
+![Magento Exam Information](./images/icon-info.png)Think EAV, think `catalog_product_entity` ➞ `eav_attribute` table ➞ (`catalog_product_entity_varchar`, `catalog_product_decimal`) etc
+
+#### eav_attributes.xml
+
+```xml
+<?xml version="1.0"?>
+
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Eav:etc/eav_attributes.xsd">
+
+    <entity type="catalog_product">
+        <attribute code="sku">
+            <field code="is_global" locked="true" />
+            <field code="is_unique" locked="true" />
+        </attribute>
+        <attribute code="status">
+            <field code="is_searchable" locked="true" />
+            <field code="is_filterable" locked="true" />
+            <field code="is_filterable_in_search" locked="true" />
+        </attribute>
+        <attribute code="visibility">
+            <field code="is_searchable" locked="true" />
+            <field code="is_filterable" locked="true" />
+            <field code="is_filterable_in_search" locked="true" />
+        </attribute>
+        <attribute code="country_of_manufacture">
+            <field code="is_searchable" locked="true" />
+            <field code="is_filterable" locked="true" />
+            <field code="is_filterable_in_search" locked="true" />
+        </attribute>
+        <attribute code="price_type">
+            <field code="is_searchable" locked="true" />
+        </attribute>
+        <attribute code="name">
+            <field code="is_html_allowed_on_front" locked="true"/>
+        </attribute>
+        <attribute code="category_ids">
+            <field code="is_global" locked="true" />
+            <field code="is_searchable" locked="true" />
+            <field code="used_for_sort_by" locked="true" />
+            <field code="is_used_in_grid" locked="true" />
+            <field code="is_visible_in_grid" locked="true" />
+            <field code="is_filterable_in_grid" locked="true" />
+        </attribute>
+        <attribute code="media_gallery">
+            <field code="is_searchable" locked="true" />
+        </attribute>
+        <attribute code="tier_price">
+            <field code="used_for_sort_by" locked="true" />
+        </attribute>
+    </entity>
+</config>
+```
+
+Getter/Setter
+```php
+Magento\Customer\Api\Data\AddressInterface::getCustomAttribute(
+    $attributeCode
+); // Get the Custom (EAV) Attribute
+
+Magento\Customer\Api\Data\AddressInterface::setCustomAttribute(
+    $attributeCode,
+    $attributeValue
+); // Set the Custom (EAV) Attribute
+
+Magento\Customer\Api\AddressRepositoryInterface::save(
+    Magento\Customer\Api\Data\AddressInterface $address
+);  // Save the entity
+ ```
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Extension Attributes
+
+> When adding new attributes to entities, We can't change the interface each time we want to add a new attribute as we would lose backwards compatibility. Our logic has to be in line with the [Service Contracts](#h.i0qq8aqgijv7) design pattern (mentioned earlier). Third-party developers cannot change the API Data interfaces defined in the Magento Core code. However, most of these entities have a feature called Extension Attributes.
+>
+> To check if an entity supports Extension Attributes, check the Api/ interface of the entity in mind for methods:
+
+*   `getExtensionAttributes()`
+*   `setExtensionAttributes()`
+
+> This will determine if they are available for that entity.
+>
+> You can also check if your entity extends interface `Magento\Framework\Api\ExtensibleDataInterface` - to decipher if they are compatible with Extension Attributes
+>
+> Extension Attributes are new in Magento 2. They are used to extend functionality and often use more complex data types than [Custom Attributes](#h.k3zjo176fdlt) (above).
+>
+> Features
+>
+> Extension Attributes do not appear in the Magento Admin.
+>
+> Extension Attributes are created using:
+
+*   [Data Patches](https://devdocs.magento.com/guides/v2.3/extension-dev-guide/declarative-schema/data-patches.html&sa=D&ust=1609223264830000&usg=AOvVaw13nYcuIOQjAQiYrtmRsgiJ). Using a Setup Factory e.g. Magento\Customer\Setup\CustomerSetupFactory
+*   Creating a [Service Contract](#h.i0qq8aqgijv7) which implements interface Magento\Framework\Api\ExtensibleDataInterface.
+*   Declarative Schema: `<module_dir>/etc/extension_attributes.xml`
+
+> Extension Attributes have the advantage of declarative schema and are defined in `<module_dir>/etc/extension_attributes.xml`
+>
+> Extension Attributes are used to extend functionality and often use more complex data types than custom or eav attributes. These attributes do not appear in the Magento Admin.
+>
+> extension_attributes.xml is used for declaring the extension attributes for the module.
+
+#### extension_attributes.xml
+
+```xml
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Api/etc/extension_attributes.xsd">
+    <extension_attributes for="Magento\Sales\Api\Data\OrderInterface">
+        <attribute code="name_of_attribute" type="<DATA_TYPE>">
+            <resources>
+                <resource ref="<PERMISSION>"/>
+            </resources>
+            <join reference_table="" reference_field="" join_on_field="">
+                <field>fieldname</field>
+            </join>
+        </attribute>
+    </extension_attributes>
+</config>
+```
+
+| Properties | Field | Description | Example |
+| --- | --- | --- | --- |
+| `<extension_attributes>` | Attributes: `for` - The fully-qualified type name with the namespace that processes the extensions. The value must be a type that implements `ExtensibleDataInterface`. The interface can be in a different module. Elements: Field: `<attribute>` | `Magento\Quote\Api\Data\TotalsInterface` |
+| `<attribute>` | Attributes: `code` - The name of the attribute. The attribute name should be in snake case (the first letter in each word should be in lowercase, with each word separated by an underscore). `type` - The data type. This can be a simple data type, such as string or integer, or complex type, such as an interface. Elements - Field: `<resources>`, Field: `<join>` | `code` : `gift_cards_amount_used`, `type` - `float`, `Magento\CatalogInventory\Api\Data\StockItemInterface` |
+| `<resources>` | Elements: Field: `<resource>` | |
+| `<resource>` | Attributes: `ref` - Optional. Restricts access to the extension attribute to users with the specified permission. Elements: Field - `<resource>` | `Magento_CatalogInventory::cataloginventory` |
+| `<join>` | Attributes: `reference_table` - The table involved in a join operation. [See Searching Extension Attributes](https://devdocs.magento.com/guides/v2.3/extension-dev-guide/attributes.html%23search&sa=D&ust=1609223264844000&usg=AOvVaw1LwiBr2j-FftDHXe8-7zbF) for details. `reference_field`: Column in the reference_table. `join_on_field`: The column of the table associated with the interface specified in the for keyword that will be used in the join operation. Elements: Field - `<field>` | `reference_table`: `admin_user`, `reference_field`: `user_id`, `join_on_field`: `store_id`. [Here is a good article](https://fishchenko.com/blog/magento-2-join-table-in-orderrepositorygetlist-extension-attributes/&sa=D&ust=1609223264847000&usg=AOvVaw1axgrEfJhYCZBW4s8b9AlM) on how to access the Join Processor from the extended class. |
+| `<field>` | One or more fields present in the interface specified in the type keyword. You can specify the `column=""` keyword to define the column in the `reference_table` to use. The field value specifies the property on the interface which should be set. | `<field column="customer_group_code">code</field>` |
+
+
+> In your concrete class implementation of the above data interface will look something like:
+```php
+namespace <MY>\<MODULE>\Model\Data;
+
+class ExampleAttribute implements <MY>\<MODULE>\Api\Data\<ExampleAttributeInterface
+{
+    /**
+     * {@inheritdoc}
+     */
+    public function getValue()
+    {
+        return $this->getData(self::VALUE);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function setValue($value)
+    {
+        return $this->setData(self::VALUE, $value);
+    }
+}
+```
+![Magento Exam Information](./images/icon-info.png)[Extension Attributes](#h.aqe3c923mrz4) are not magically saved to the database or populated when the quote or order, etc is loaded from the database.
+
+![Magento Exam Information](./images/icon-info.png) `type="<DATA_TYPE>"` Can be scalar / non-scalar, meaning either: string or `<MY>\<MODULE>\Api\Data\<ExampleAttributeInterface>` or `string[]`
+
+![Magento Exam Information](./images/icon-info.png)This means that we are extending our Sales Order Interface with an attribute. It's accessible via `$order->getExtensionAttributes()->getNameOfAttribute()`.
+
+![Magento Exam Information](./images/icon-info.png)[Here is a good article](https://fishchenko.com/blog/magento-2-join-table-in-orderrepositorygetlist-extension-attributes/&sa=D&ust=1609223264850000&usg=AOvVaw3BeT6r7k6d3f8Db4JZBUHE) on how to access the Join Processor from the extended class
+
+![Magento Exam Information](./images/icon-info.png)[Here's a great guide](https://store.fooman.co.nz/blog/an-introduction-to-extension-attributes.html&sa=D&ust=1609223264851000&usg=AOvVaw3fKCSQfPQRXzfs69ukWnJy) on what Extension Attributes.
+
+![Magento Exam Information](./images/icon-info.png)Extension Attributes Advantages = declarative schema, can involve more complex data types, they are in-line with Service Contract design pattern, are better for backward compatibility rather than changing core interfaces.
+
+Saving and retrieving
+
+Saving [Extension Attributes](#h.aqe3c923mrz4) will require a custom persistence layer for storage. Therefore, the rest of the [Service Contracts](#h.i0qq8aqgijv7) will need to be created i.e. a custom:
+
+*   [Repository](#h.5y2r6c8djm3h)
+*   [Resource Model](#h.h64lcrmfa6jp)
+*   [Collection](#h.ovkq1s5o8zg)
+*   [Search Criteria](#h.5y2r6c8djm3h)
+*   [Declarative Schema](#h.iqvl9uln4170)
+
+will be required.
+
+[Extension Attributes](#h.aqe3c923mrz4) are not magically saved to the database or populated when the quote or order, etc is loaded from the database. Therefore you will need to set them using a [Plugin Interceptor](#h.nc1ow1wmf2km) or an [Observer](#h.y2lezqicnwxl). Here is an example of a Plugin:
+`etc/di.xml`
+```xml
+<?xml version="1.0"?>
+
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
+    <type name="Magento\Sales\Api\OrderRepositoryInterface">
+        <plugin name="save_example_attribute" type="MyVendor\MyModule\Plugin\OrderSave"/>
+        <plugin name="get_example_attribute" type="MyVendor\MyModule\Plugin\OrderGet"/>
+    </type>
+</config>
+```
+```php
+<?php
+
+namespace MyVendor\MyModule\Plugin;
+
+use Magento\Framework\Exception\CouldNotSaveException;
+
+class OrderSave
+{
+    public function afterSave(
+        \Magento\Sales\Api\OrderRepositoryInterface $subject,
+        \Magento\Sales\Api\Data\OrderInterface $resultOrder
+
+    ) {
+        $resultOrder = $this->saveExampleAttribute($resultOrder);
+        return $resultOrder;
+    }
+
+    private function saveExampleAttribute(\Magento\Sales\Api\Data\OrderInterface $order)
+    {
+        $extensionAttributes = $order->getExtensionAttributes();
+        if (
+            null !== $extensionAttributes &&
+            null !== $extensionAttributes->getExampleAttribute()
+        ) {
+
+            $exampleAttributeValue = $extensionAttributes->getExampleAttribute()->getValue();
+
+            try {
+
+                // The actual implementation of the repository is omitted
+                // but it is where you would save to the database (or any other persistent storage)
+                $this->exampleExampleRepository->save($order->getEntityId(), $exampleAttributeValue);
+            } catch (\Exception $e) {
+
+                throw new CouldNotSaveException(
+                    __('Could not add attribute to order: "%1"', $e->getMessage()),
+                    $e
+                );
+            }
+        }
+
+        return $order;
+    }
+}
+
+```
+![Magento Exam Question](./images/icon-question.png)**What is the difference between Custom Attributes and Extension Attributes**
+
+> [Custom Attributes](#h.k3zjo176fdlt) are the attributes added to describe an entity, such as product attributes, customer attributes etc. These are a subset of EAV attributes.
+>
+>
+> [Extension Attributes](#h.aqe3c923mrz4) on the other hand are generally used for more complex data types such as adding additional complex data into an entity from a custom external table.
+> Simply put, custom attributes conform to EAV standards whereas extension attributes are used for more complex data which custom attributes cannot handle.
+
+![Magento Exam Question](./images/icon-question.png)**How do you select a subset of records from the database?**
+
+> Use `addFieldToSelect` and `addAttributeToSelect` methods of a Collection to specify the fields for selection.
+>
+> For example:
+>
+>    `$productCollection->addFieldToSelect("custom_field");`
+>
+> To apply filters to collections, use
+>
+>    `addAttributeToFilter($field, $condition)`
+>
+>    `addFieldToFilter($field, $condition)`
+
+Conditions can be one of the following:
+
+### Where Query Operators
+
+| Magento Associative Array Condition | MySQL Condition |
+| --- | --- |
+| `"eq"` | Equals Value |
+| `"neq"` | Not Equal Value |
+| `"like"` | Like Value |
+| `"nlike"` | Not Like Value |
+| `"is"` | Is Value |
+| `"in"` | In Values |
+| `"nin"` | Not In Values |
+| `"notnull"` | Value Is Not Null |
+| `"null"` | Value Is Null, example: `$c->prepareSqlCondition('finished_at', ['null' => NULL])` |
+| `"moreq"` | More Or Equal Value
+| `"gt"` | Greater Value |
+| `"lt"` | Less Value |
+| `"gteq"` | Greater Or Equal Value |
+| `"lteq"` | Less Or Equal Value |
+| `"finset"` | Value In Set |
+| `"from" => "value", "to" => "value"` | In Between "from" & "to" Values |
+
+
+> Example:
+>
+> `$productCollection->addFieldToFilter('entity_id', array('in' => [1,2,3])`
+>
+> `setOrder` method is used for sorting and processes both filter and direction fields. For instance:
+>
+> `$productCollection>setOrder('position','ASC');`
+>
+> `searchCriteria` is used for applying filters in repositories. More on that above.
+
+![Magento Exam Question](./images/icon-question.png)**Describe the Database Abstraction Layer for Magento.**
+
+> The Database Abstraction Layer performs generic database operations like connections, commands, parameters insulating you from vendor specific data libraries and providing one high level api for accessing data regardless of whether you use MySQL, Microsoft SQL Server, Oracle, DB2, etc...
+
+![Magento Exam Information](./images/icon-info.png)The Resource Model of each Entity acts as the Database Abstraction Layer.
+
+![Magento Exam Information](./images/icon-info.png)This gives Magento 2 the ability to better plug-in and out different DB management systems such as Postgres SQL - Which they might start diving into in the near future.
+
+![Magento Exam Question](./images/icon-question.png)**What type of exceptions does the database layer throw?**
+
+> Database layer can put out exceptions depending on its realization. For example,
+> PDO/Mysql can put out the following exceptions:
+
+*   Zend_Db_Adapter_Exception
+*   Zend_Db_Statement_Exception
+*   Zend_Db_Exception
+*   Zend_Db_Statement_Pdo
+*   PDOException
+*   LocalizedException
+*   InvalidArgumentException
+*   Exception
+*   DuplicateException
+
+![Magento Exam Information](./images/icon-info.png)Not certain how important this is to learn really.
+
+![Magento Exam Question](./images/icon-question.png)**What additional functionality does Magento provide over Zend_Adapter?**
+
+> The following additional methods are realized atop Zend_Adapter:
+
+*   addUniqueField
+*   unserializeFields
+*   serializeFields
+*   hasDataChanged
+*   prepareDataForUpdate
+*   isObjectNotNew
+*   saveNewObject
+*   afterSave
+*   beforeSave
+*   isModified
+*   afterLoad
+*   beforeDelete
+*   afterDelete
+
+![Magento Exam Information](./images/icon-info.png)Not certain how important this is to learn really.
+
+4.2 Demonstrate an ability to use declarative schema
+----------------------------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**Demonstrate use of schema.**
+
+> Schema setup scripts change database schema, they create or change needed database tables.
+
+![Magento Exam Information](./images/icon-info.png)i.e Create a new table and its fields with its structure.
+
+![Magento Exam Question](./images/icon-question.png)**How to manipulate columns and keys using declarative schema?**
+
+![Magento Section Chevron](./images/icon-chevron.png) `db_schema.xml`
+
+> Magento prioritizes the declarative schema approach and executes updates from the [db_schema.xml](https://devdocs.magento.com/guides/v2.3/extension-dev-guide/declarative-schema/db-schema.html&sa=D&ust=1609223264887000&usg=AOvVaw3s2_fjZNEGX96-L5Vm0X92) before the data and schema patches.
+
+![Magento Exam Information](./images/icon-info.png)All database related extension or manipulation all belong in the `<module_dir>/Setup` directory. A good example would be the [Magento_Catalog](https://github.com/magento/magento2/blob/2.3/app/code/Magento/Catalog/etc/db_schema.xml&sa=D&ust=1609223264888000&usg=AOvVaw3m3468kc66q7g7KAms8WeZ)
+
+![Magento Exam Information](./images/icon-info.png)Schema is used to create/update DB tables and its structure. While Data is used to insert/add data into tables.
+
+Example `db_schema.xml`:
+```xml
+<?xml version="1.0"?>
+<schema xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Setup/Declaration/Schema/etc/schema.xsd">
+    <table name="my_table" resource="default" engine="innodb" comment="Example Table">
+        <column xsi:type="int" name="entity_id" padding="10" unsigned="true" nullable="false" identity="true" comment="ID"/>
+        <column xsi:type="varchar" name="name" comment="Name"/>
+        <column xsi:type="varchar" name="body" comment="Body"/>
+        <constraint xsi:type="primary" referenceId="PRIMARY">
+            <column name="entity_id"/>
+        </constraint>
+        <index referenceId="Vendor_MyModule_TABLE1_ID" indexType="btree">
+            <column name="entity_id"/>
+        </index>
+    </table>
+</schema>
+```
+| Field | Description |
+| --- | --- |
+| `<table>` | Attributes: `name` - Name of the table. `comment` - Comment for the table. `engine` - SQL engine. This value must be innodb or memory. `resource` - The database shard on which to install the table. This value must be "default", "checkout", or "sales". Elements `<column>` |
+| `<column>` | Attributes: `xsi:type` - Column types include: blob (includes blob, mediumblob, longblob), boolean, date, datetime, decimal, float, int (includes smallint, bigint, tinyint), real (includes decimal, float, double, real), smallint, text (includes text, mediumtext, longtext), timestamp, varbinary, varchar. `name` - Column name. `padding` - The size of an integer column. `usigned` - For numeric data types, specifies whether the column can contain positive and negative values or only positive values. `nullable` - Indicates whether the column can be nullable. `identity` - Indicates whether a column is auto-incremented. `comment` - Comment for the column. |
+| `<constraint>` | Attributes: `type` - One of "primary", "unique", or "foreign". `referenceId` - A custom identifier that is used only for relation mapping in the scope of `db_schema.xml` files. The real entity in the database has a system-generated name. The most convenient way to set the value of this attribute is to use the value that is written in the module's `db_schema_whitelist.json` file when you run the generate-whitelist command. **NOTE:** ensure your foreign key constraint matches the same type as the referencing column, otherwise you risk the misleading "MySQL: Foreign key constraint is incorrectly formed" error. |
+| `<index>` | Attributes: `indexType` - The value must be "btree", "fulltext", or "hash". `referenceId` - A custom identifier that is used only for relation mapping in the scope of db_schema.xml files. The real entity in the database has a system-generated name. The most convenient way to set the value of this attribute is to use the value that is written in the module's `db_schema_whitelist.json` file when you run the generate-whitelist command. |
+
+![Magento Exam Question](./images/icon-question.png)**What is the purpose of whitelisting?**
+
+> The db_schema_whitelist.json file is a way of telling Magento which tables and columns it can safely alter using the db_schema.xml It was added to preserve backward compatibility. Since Backward compatibility must be maintained, declarative schema does not automatically delete database tables, columns or keys that are not defined in a db_schema.xml as they can be declared somewhere else such as Setup/UpgradeSchema.php
+>
+> The Magento 2.3+ version of the command to generate a <module_dir>/etc/db_schema_whitelist.json file:
+>
+> `php bin/magento declaration:generate:whitelist`
+
+![Magento Exam Note Warning](images/icon-warning.png)`db_schema_whitelist.json` is a temporary solution. It will be removed in the future, when upgrade scripts are no longer supported.
+
+![Magento Exam Note Warning](images/icon-warning.png)Whitelists cannot be generated on Magento instances that use a database prefix.
+
+Example of a `db_schema_whitelist.json` file:
+```json
+{
+    "my_table_1": {
+        "column": {
+            "column_1": true,
+            "column_2": true,
+            "column_3": true
+        },
+        "index": {
+            "MY_TABLE_1_COLUMN_1": true
+        },
+        "constraint": {
+            "PRIMARY": true
+        }
+    },
+    "my_table_2": {
+        ……
+    }
+}
+```
+![Magento Exam Question](./images/icon-question.png)**How to use Data and Schema patches?**
+
+### ![Magento Section Chevron](./images/icon-chevron.png) Data Patches
+
+> A Data Patch is a Setup class that contains data modification instructions.
+>
+> Data Patches and belong in a `<module_dir>/Setup/Patch/Data/<patch_name>.php` directory of a custom [Module](#h.8r6t4fakpxnh).
+
+```php
+<?php
+
+namespace Magento\DummyModule\Setup\Patch\Data;
+
+use Magento\Framework\Setup\Patch\DataPatchInterface;
+use Magento\Framework\Setup\ModuleDataSetupInterface;
+use Magento\Framework\Setup\Patch\PatchRevertableInterface;
+
+class DummyDataPatch implements DataPatchInterface, PatchRevertableInterface
+{
+    /**
+     * @var ModuleDataSetupInterface
+     */
+    private $moduleDataSetup;
+
+    /**
+     * @param ModuleDataSetupInterface $moduleDataSetup
+     */
+    public function __construct(ModuleDataSetupInterface $moduleDataSetup)
+    {
+        $this->moduleDataSetup = $moduleDataSetup;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function apply()
+    {
+        $this->moduleDataSetup->getConnection()->startSetup();
+        // The code that you want apply in the patch
+        $this->moduleDataSetup->getConnection()->endSetup();
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+
+    public static function getDependencies()
+    {
+        return [
+            SomeDependency::class
+        ];
+    }
+
+    public function revert()
+    {
+        $this->moduleDataSetup->getConnection()->startSetup();
+        // Revert operations here
+        $this->moduleDataSetup->getConnection()->endSetup();
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getAliases()
+    {
+        return [];
+    }
+}
+
+```
+> `apply()` - The code that you want to apply in the patch goes here. Please note, that one patch is responsible only for one setup version. So one UpgradeData can consist of a few data patches.getAliases() - This internal Magento method, that means that some patches with time can change their names, but changing name should not affect installation process, that's why if we will change name of the patch we will add alias here
+>
+> `revert()` - Mentioned below
+>
+> `getDependencies()` - Mentioned below
+
+![Magento Exam Information](./images/icon-info.png)Data setup is executed after Schema setup, they function in a similar fashion.
+
+![Magento Exam Information](./images/icon-info.png)A list of applied patches is stored in the `patch_list` database table.
+
+![Magento Exam Information](./images/icon-info.png)Just remember that Patches contain data modification instructions. They implement `DataPatchInterface` & `PatchRevertableInterface` and are located in `<module_dir>/Setup/Patch/Data/<patch_name>.php`
+
+![Magento Section Chevron](./images/icon-chevron.png) Reverting Data Patches
+
+> Magento does not allow you to revert a particular module data patch. However, you can revert all installed data patches of a single module.Run the following command to revert all composer installed data patches:
+>
+> `bin/magento module:uninstall Vendor_ModuleName`
+>
+> Run the following command to revert all non-composer installed data patches:
+>
+> `bin/magento module:uninstall --non-composer Vendor_ModuleName`
+>
+> This will run the public function `revert()` method of your modules `Magento\Framework\Setup\Patch\PatchRevertableInterface` implementation.
+>
+> `revert()` - Here should go code that will revert all operations from apply() method. Please note that some operations, like removing data from columns, that is in the role of foreign key reference is dangerous, because it can trigger an `ON DELETE` statement.
+
+### ![Magento Section Chevron](./images/icon-chevron.png) Schema Patches
+
+> A Schema Patch is a Setup class that contains custom schema (database) modification instructions.
+>
+> These modifications can be complex. It is defined in a `<module_dir>/Setup/Patch/Schema/<patch>.php` file and implements `Magento\Framework\Setup\Patch\SchemaPatchInterface`.
+
+![Magento Exam Information](./images/icon-info.png)Unlike the declarative schema approach, patches will only be applied once. A list of applied patches is stored in the patch_list database table. An unapplied patch will be applied when running the setup:upgrade from the Magento CLI.
+
+> Schema Patches and belong in a `<module_dir>/Setup/Patch/Schema/<patch_name>.php` directory of a custom Module.
+
+```php
+<?php
+
+namespace Magento\DummyModule\Setup\Patch\Schema;
+
+use Magento\Framework\Setup\Patch\SchemaPatchInterface;
+use Magento\Framework\Setup\ModuleDataSetupInterface;
+use Magento\Framework\Setup\Patch\PatchRevertableInterface;
+
+class DummySchemaPatch implements SchemaPatchInterface, PatchRevertableInterface
+{
+    /**
+     * @var ModuleDataSetupInterface
+     */
+    private $moduleDataSetup;
+
+    /**
+     * @param ModuleDataSetupInterface $moduleDataSetup
+     */
+    public function __construct(ModuleDataSetupInterface $moduleDataSetup)
+    {
+        $this->moduleDataSetup = $moduleDataSetup;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function apply()
+    {
+        $this->moduleDataSetup->getConnection()->startSetup();
+        // The code that you want apply in the patch
+        $this->moduleDataSetup->getConnection()->endSetup();
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public static function getDependencies()
+    {
+        return [
+            SomeDependency::class
+        ];
+    }
+
+    public function revert()
+    {
+        $this->moduleDataSetup->getConnection()->startSetup();
+        // Revert operations here
+        $this->moduleDataSetup->getConnection()->endSetup();
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getAliases()
+    {
+        return [];
+    }
+}
+
+```
+
+> `apply()` - Mentioned above
+>
+> `getAliases()` - Mentioned above
+>
+> `revert()` - Mentioned above
+>
+> `getDependencies()` - Mentioned below
+
+![Magento Exam Question](./images/icon-question.png)**How to manage dependencies between patch files?**
+
+> `getDependencies()` - defines dependencies to another patch. Each dependency should be applied first. One patch can have few dependencies. Patches do not have versions, so if in the old approach with Install/Upgrade data scripts you used versions, right now you need to point from patch with higher version to patch with lower version But please, note, that some of your patches can be independent and can be installed in any sequence. So use dependencies only if this is important for you.
\ No newline at end of file
diff --git a/5. Using the Entity-Attribute-Value -EAV- Model/2. Demonstrate ability to use EAV entity load and save.md b/5. Using the Entity-Attribute-Value -EAV- Model/2. Demonstrate ability to use EAV entity load and save.md
deleted file mode 100644
index a09f9e0..0000000
--- a/5. Using the Entity-Attribute-Value -EAV- Model/2. Demonstrate ability to use EAV entity load and save.md	
+++ /dev/null
@@ -1,158 +0,0 @@
-# Demonstrate ability to use EAV entity load and save
-
-Types of resource models:
-- flat resource - `Magento\Framework\Model\ResourceModel\AbstractResource`
-- EAV entity resource - `Magento\Eav\Model\Entity\AbstractEntity`
-- version controll aware EAV entity resource - `Magento\Eav\Model\Entity\VersionControl\AbstractEntity`.
-  Used only by customer and customer address.
-
-New Entity Manager stands aside, you don't need to extend your resource model from it,
-but rather manually call its methods in your resource - load, save, delete.
-\Magento\Framework\EntityManager\EntityManager is suitable for both flat and EAV tables.
-
-## Entity Manager
-
-Entity manager is a new way of saving both flat tables and EAV entities.
-Separates individual operations into own class - read, create, update, delete.
-This give a lot of freedom for extensions.
-
-Each operation still has a lot to do - save EAV data and run extensions. Default operations
-split these activities into smaller actions:
-- save main table - both for flat and EAV
-- save EAV attributes - only for EAV entities. see *attribute pool*
-- run extensions - see *extension pool*
-
-Entity manager is concept separate from regular flat and EAV resource models saving, it doesn't
-call them under the hood. It does the same things but in own fashion with extensibility in mind.
-
-This means that you can still build your code on regular resource models:
-- flat resource Magento\Framework\Model\ResourceModel\Db\AbstractDb
-- EAV entity resource Magento\Eav\Model\Entity\AbstractEntity
-
-Entity manager is currently used by:
-- bundle option
-- bundle selection
-- catalog rule
-- product
-- category
-- cms block
-- cms page
-- sales rule
-- gift card amount
-- and some others (staging etc.)
-
-Terms:
-- *entity manager* - calls appropiate operations. Holds type resolver and operations pool
-- *metadata pool* - DI injectable. Register Api Data interface and [`entityTableName`, `identifierField`]
-    ```xml
-    <item name="Magento\Cms\Api\Data\PageInterface" xsi:type="array">
-        <item name="entityTableName" xsi:type="string">cms_page</item>
-        <item name="identifierField" xsi:type="string">page_id</item>
-        <!-- eavEntityType - flag is eav -->
-        <!-- connectionName -->
-        <!-- sequence -->
-        <!-- entityContext -->
-    </item>
-    ```
-
-- *operation pool* - `checkIfExists`/`read`/`create`/`update`/`delete` operations per entity type. Operaton does ALL work.
-    *Default operations - can extend in DI:*
-    - checkIfExists - Magento\Framework\EntityManager\Operation\CheckIfExists - decides if entity is new or updated
-    - read - Magento\Framework\EntityManager\Operation\Read
-    - create - Magento\Framework\EntityManager\Operation\Create
-    - update - Magento\Framework\EntityManager\Operation\Update
-    - delete - Magento\Framework\EntityManager\Operation\Delete
-
-- *attribute pool* - read/create/update attributes in separate tables per entity type. DI injectable, has default, register only to override.
-    ```xml
-    <item name="Magento\Catalog\Api\Data\CategoryInterface" xsi:type="array">
-        <item name="create" xsi:type="string">Magento\Catalog\Model\ResourceModel\CreateHandler</item>
-        <item name="update" xsi:type="string">Magento\Catalog\Model\ResourceModel\UpdateHandler</item>
-    </item>
-    ```
-    *Default attribute pool actions - Module_Eav/etc/di.xml:*
-    - read - Magento\Eav\Model\ResourceModel\ReadHandler
-    - create - Magento\Eav\Model\ResourceModel\CreateHandler
-    - update - Magento\Eav\Model\ResourceModel\UpdateHandler
-
-- *extension pool* - custom modifications on entity read/create/update. Put your extensions here, good for extension attributes
-  + product gallery read/create
-  + product option read/save
-  + product website read/save
-  + configurable product links read/save
-  + category link read/save
-  + bundle product read/save - set options
-  + downloadable link create/delete/read/update
-  + gift card amount read/save
-  + cms block, cms page - store read/save
-
-
-### *Entity manager.save:*
-- resolve entity type - implementing data interface `\Api\Data` when possible, or original class
-- check `has(entity)` - detect create new or update
-  * operation pool.getOperation(`checkIfExists`)
-- if new, operation pool.getOperation(`create`).execute
-- if existing, operation pool.getOperation(`update`).execute
-- run callbacks
-
-### `create` operation
-- event `entity_manager_save_before`
-- event `{$lower_case_entity_type}_save_before`
-- apply sequence - \Magento\Framework\EntityManager\Sequence\SequenceApplier::apply
-  * entity[id] = sequence.getNextValue
-- *create main*
-  * EntityManager\Db\CreateRow::execute - insert into main table by existing column
-- *create attributes*
-  * attribute pool actions `create`[].execute
-  * default action handler `Magento\Eav\Model\ResourceModel\CreateHandler`:
-    + only if entity is EAV type, insert all attributes
-      - \Magento\Eav\Model\ResourceModel\AttributePersistor::registerInsert
-      - \Magento\Eav\Model\ResourceModel\AttributePersistor::flush
-- *create extensions* - \Magento\Framework\EntityManager\Operation\Create\CreateExtensions
-  * extension pool actions `create`[].execute - save many-to-many records, custom columns etc.
-- event `{$lower_case_entity_type}_save_after`
-- event `entity_manager_save_after`
-
-
-## Object converters
-\Magento\Framework\Reflection\DataObjectProcessor::buildOutputDataArray(object, interface)
-\Magento\Framework\Reflection\CustomAttributesProcessor::buildOutputDataArray
-\Magento\Framework\Reflection\ExtensionAttributesProcessor::buildOutputDataArray
-
-
-\Magento\Framework\Api\\`SimpleDataObjectConverter`:
-- toFlatArray:
-  * data object processor.buildOutputDataArray
-  * ConvertArray::toFlatArray
-- convertKeysToCamelCase - used by Soap API, supports `custom_attributes`
-
-\Magento\Framework\Api\\`ExtensibleDataObjectConverter`:
-- toNestedArray(entity, skip custom attributes list, interface) - used by entity repositories.save:
-  * data object processor.buildOutputDataArray
-  * add `custom_attributes`
-  * add `extension_attributes`
-- toFlatArray:
-  * toNestedArray
-  * ConvertArray::toFlatArray
-- (static) convertCustomAttributesToSequentialArray
-
-
-\Magento\Framework\Reflection\DataObjectProcessor::buildOutputDataArray:
-- \Magento\Framework\Reflection\MethodsMap::getMethodsMap - method name and getter return types
-- filter only getters: is..., has..., get...
-- get data using interface getter, e.g. $object->getSku() - based on Interface definition
-- deduce field name by getter name, e.g. 'sku'
-- process custom_attributes \Magento\Framework\Reflection\CustomAttributesProcessor::buildOutputDataArray
-- process extension_attributes \Magento\Framework\Reflection\ExtensionAttributesProcessor::buildOutputDataArray
-- process return object: build return value objects with their return type annotation
-- process return array: cast each element to type, e.g. int[] => (int) each value
-- cast element to type
-
-Product.save:
-- buildOutputDataArray
-- product data = call all getters + original data
-- product = initializeProductData. create new product/get existing by SKU. set product data
-- process links, unless product data `ignore_links_flag`
-- abstract entity.validate
-- product resource.save
-- entity manager.save
diff --git a/5.Magento-Using-Entity-Attribute-Value-Model.md b/5.Magento-Using-Entity-Attribute-Value-Model.md
new file mode 100755
index 0000000..30502b9
--- /dev/null
+++ b/5.Magento-Using-Entity-Attribute-Value-Model.md
@@ -0,0 +1,823 @@
+5 - Using the Entity-Attribute-Value (EAV) Model
+================================================
+
+5.1 Demonstrate ability to use EAV model concepts
+-------------------------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**Describe how EAV data storage works in Magento. Describe the EAV hierarchy structure.**
+
+> EAV (Entity-attribute-value) is a model for storing entity attribute values ​​in a certain storage place. For storage, Magento 2 supports MySQL-compatible databases.
+>
+> The table of the classic EAV model has 3 columns:
+
+1.  Entity (object to which the attribute value must be set)
+2.  Attribute
+3.  Value
+
+> Whereas Magento has 5:
+
+1.  A `backend_type` e.g. varchar, int, text etc is assigned for each attribute.
+2.  Table eav_entity_type stores each custom and system EAV entity type separately (e.g. `catalog_product_entity`, `customer_address_entity`, sales_order etc). It's purpose is to name the tables where the entities are stored via the entity_table column. See [Section 5.3 EAV Attribute Features](#h.v4fzn8rafjf4) for available types.
+3.  Table eav_entity holds system EAV entities - those that are available out-of-the-box
+4.  Attributes with a `backend_type` as "static", are stored in the same table as entities. These attributes have global scope.
+5.  Each `backend_type` of each entity type has its own table e.g. "`catalog_product_entity_int`", "`catalog_product_entity_decimal`", in which attribute values are stored. The name of this table is crafted according to the template {entity_table} _ {`backend_type`}, where entity_table is the name of the entity table and `backend_type` is the backend type of the attribute. These tables include the following columns:
+    *  `value_id` (int)
+    *  `attribute_id` (int)
+    *  `store_id` (int)
+    *  `entity_id` (int)
+    *  `value` (type depends on the backend type).
+
+![Magento Exam Question](./images/icon-question.png)**What happens when a new attribute is added to the system? (what frontend input's are available when adding a new attribute to the system).**
+
+![Magento Section Chevron](./images/icon-chevron.png) Text Attributes
+
+1.  A new record in eav_attribute table is made.
+2.  One entry per store view is created in the eav_attribute_label table with the Label attribute.
+3.  A new record in the catalog_eav_attribute table is created.
+
+![Magento Section Chevron](./images/icon-chevron.png) Dropdown (dynamic) Attributes
+
+For attributes with varying options, there are a few additional differences to the above, chiefly:
+
+1.  eav_attribute.frontend_input = "select"
+2.  eav_attribute.source_model = "Magento\Eav\Model\Entity\Attribute\Source\Table"
+3.  eav_attribute.`backend_type` = "int"
+4.  eav_attribute.default_value = eav_attribute_option.option_id by default
+5.  Each option are added to table eav_attribute_option
+
+![Magento Section Chevron](./images/icon-chevron.png) Price Attributes
+
+Differences compared to Text Field:
+
+1.  eav_attribute.frontend_input = "price"
+2.  eav_attribute.backend_model = "Magento\Catalog\Model\Product\Attribute\Backend\Price"
+3.  eav_attribute.`backend_type` = "decimal"
+
+![Magento Section Chevron](./images/icon-chevron.png)Media Image
+
+Differences compared to Text Field:
+
+1.  eav_attribute.frontend_input = "media_image"
+
+![Magento Section Chevron](./images/icon-chevron.png)Text swatch
+
+Differences compared to Dropdown:
+
+1.  catalog_eav_attribute.additional_data is in JSON output: {"swatch_input_type":"text","update_product_preview_image":"0″,"use_product_image_for_swatch":0}
+2.  Each swatch option is added to eav_attribute_option_swatch
+
+![Magento Exam Information](./images/icon-info.png)See Section [5.3 EAV Attribute Features](#h.v4fzn8rafjf4) for available types.
+
+![Magento Exam Question](./images/icon-question.png)**What is the role of attribute sets and attribute groups?**
+
+> Attribute Set's are applied to display different attributes for various products (eg. shoes and clothes). For example, if we have "shoe_size" and "clothing_size" attributes, and we need to display the first one for shoes, and the second - for clothes. An Attribute Set allows us to hide the unnecessary attributes, display the needed ones, modify the sorting and group.
+>
+> Groups simplify the process of filling product information by the administrator, but have no effect on product loading / storing logic.
+>
+> Attributes in attribute set settings:
+>
+> **Admin > Stores > Attributes > Attribute Sets**
+
+![Magento Exam Question](./images/icon-question.png)**How are Attributes presented in the admin?**
+
+> Product Attributes consist of a Name (label) and a Field (value) of which the administrator can change.
+>
+> The following attribute properties affect the display:
+
+*   `frontend_model` - a class that describes the field display in the frontend section of a site. Inherited from `Magento\Eav\Model\Entity\Attribute\Frontend\AbstractFrontend` and overrides the `getValue()` method to change the displayed attribute values
+*   `frontend_input` (Catalog Input Type for Store Owner) - The form element that is displayed in the admin section of the site. This can only be selected once per attribute.
+*   `frontend_label` (Default Label) - the name of the attribute, displayed in the admin section of the site. It is also displayed in the site frontend, unless otherwise specified in the `eav_attribute_label` table (in the attribute settings it is changed in the "Manage Labels" tab)
+*   `frontend_class` (Input Validation for Store Owner) - used to validate the attribute value in the admin section of the site. In the attribute settings, the property is called Input Validation for Store Owner. For email validation, the `frontend_class` property is set to "`validate-email`".
+
+![Magento Exam Information](./images/icon-info.png)See Section [5.3 EAV Attribute Features](#h.v4fzn8rafjf4) for available types, models & classes.
+
+![Magento Exam Question](./images/icon-question.png)**Which additional options do you have when saving EAV entities?**
+
+![Magento Section Chevron](./images/icon-chevron.png)The EAV entity modification page offer the following capabilities:
+
+> Default Attribute Values. Allows to set the value that will be inserted into the attribute field if it is not filled in. This simplifies the process of adding and modifying the entities. These are the potential default attribute values for the product:
+
+*   Text Field - any one-line text
+*   Textarea - any multi-line text
+*   Date - any date
+*   Yes/No - yes or no
+*   Multiple Select - any number of options
+*   Dropdown - one option
+*   Price - no default value
+*   Media Image - no default value
+*   Visual Swatch - one option
+*   Text Swatch - one option
+*   Fixed Product Tax - no default value
+
+![Magento Section Chevron](./images/icon-chevron.png)Scope selection.
+
+> Scope allows to set different attribute values for different websites / stores / views. Below is a list of the possible attribute scope for the product:
+
+*   Text Field - store view / website / global
+*   Textarea - store view / website / global
+*   Date - store view / website / global
+*   Yes/No - store view / website / global
+*   Multiple Select - store view / website / global
+*   Dropdown - store view / website / global
+*   Price - website / global (configured in Stores > Configuration > Catalog > Catalog > Price > Catalog Price Scope)
+*   Media Image - store view / website / global
+*   Visual Swatch - store view / website / global
+*   Text Swatch - store view / website / global
+*   Fixed Product Tax - global
+
+![Magento Exam Information](./images/icon-info.png)I think the important thing here to remember is that all default attributes are configurable down to a store view level except Fixed Product Tax and Price (price is a per website thing).
+
+![Magento Section Chevron](./images/icon-chevron.png) Attribute Set Selection (products only).
+
+> Allows to regroup or hide the attributes that do not suit the current product type. See above for more info on Attribute Sets.
+
+![Magento Section Chevron](./images/icon-chevron.png)EAV Entity Validation.
+
+> Before saving an EAV entity at the client side, we have the following features:
+
+*   Prohibition to save entities, if there are empty attribute fields with the is_required = 1 feature. It allows us to define what attributes of the entity are required to be filled in.
+*   Validation of the attribute fields values by the algorithm, set in frontend_class. The following frontend classes are supported by default it Magento:
+*   `validate-number`: Decimal Number
+*   `validate-digits`: Integer Number
+*   `validate-email`: Email
+*   `validate-url`: URL
+*   `validate-alpha`: Letters
+*   `validate-alphanum`: Letters (a-z, A-Z) or Numbers (0-9)
+
+
+Before saving an EAV entity at the server side, we have the following features:
+
+*   Check attribute fields with `is_required = 1` for fullness. Magento checks the required fields on both the client and server sides.
+*   Uniqueness check of the attribute fields with `is_unique = 1`.
+*   Perform operations in `backend_model`:
+*   Validation (validate method). Allows to realize additional server check before saving.
+*   Operation before saving (`beforeSave` method).
+*   Operation after saving (`afterSave` method).
+
+![Magento Exam Information](./images/icon-info.png)Basically there is frontend and backend validation, before and after methods and a backend_model for those more complex attributes.
+
+![Magento Section Chevron](./images/icon-chevron.png) Additional Attribute Parameters
+
+> Module catalog has an additional catalog_eav_attribute table for attributes, where the following parameters are stored:
+
+*   Frontend Input Renderer
+*   Is Global
+*   Is Visible
+*   Is Searchable
+*   Is Filterable
+*   Is Comparable
+*   Is Visible On Front
+*   Is HTML Allowed On Front
+*   Is Used For Price Rules
+*   Is Filterable In Search
+*   Is Used In Product Listing
+*   Is Used For Sorting
+*   Is Visible In Advanced Search
+*   Is WYSIWYG Enabled
+*   Is Used For Promo Rules
+*   Is Required In Admin Store
+*   Is Used in Grid
+*   Is Visible in Grid
+*   Is Filterable in Grid
+
+> These parameters allow us to perform a more sophisticated attribute configuration.
+
+![Magento Exam Information](./images/icon-info.png)These are all available parameters a user can select when creating attributes in the admin. Just gotta think back and remember them!
+
+![Magento Exam Question](./images/icon-question.png)**How do you create customizations based on changes to attribute values?**
+
+> To customize an attribute, modify the following attribute features:
+
+*   `backend_model` - The model is used for processing and validating the attribute values. By default, `Magento\Eav\Model\Entity\Attribute\Backend\DefaultBackend` is used. More info on this in the above "EAV Entity Validation" subsection.
+*   `source_model` - The model is used for providing the list of the attribute values. By default, `Magento\Eav\Model\Entity\Attribute\Source\Config` is used. You can choose to extend it to leverage the `getAllOptions()` method.
+*   `attribute_model` - The model allows us to perform a more sophisticated attribute setting. By default, `Magento\Eav\Model\Entity\Attribute` is used, and a model, different from the default one, is rarely applied.
+*   `frontend_model` - Frontend model is used for displaying the frontend part of the website. By default, `Magento\Eav\Model\Entity\Attribute\Frontend\DefaultFrontend` is applied, but you can extend it to leverage the `getValue()` method.
+
+![Magento Exam Question](./images/icon-question.png)**Describe the key differences between EAV and flat table collections.**
+
+> Magento typically stores catalog data in multiple tables, based on the Entity-Attribute-Value (EAV) model. Because product attributes are stored in many tables, SQL queries are sometimes long and complex.
+>
+> In contrast, a flat catalog creates new tables on the fly, where each row contains all the necessary data about a product or category. A flat catalog is updated automatically - either every minute, or according to your cron job. Flat catalog indexing can also speed up the processing of Catalog and [Cart Price Rules](#h.x0kvcqk03fp8). A catalog with as many as 500,000 SKUs can be indexed quickly as a flat catalog.
+>
+> Flat Catalog is configured in:
+>
+> **Admin > Stores > Configuration > Catalog > Catalog > Use Flat Catalog Category**
+>
+> **Admin > Stores > Configuration > Catalog > Catalog > Use Use Flat Catalog Product**
+
+![Magento Exam Note Warning](images/icon-warning.png)Magento no longer recommends the use of a flat catalog as a best practice. Continued use of this feature is known to cause performance degradation and other indexing issues in Magento 2.1 and below.
+
+![Magento Exam Question](./images/icon-question.png)**In which situations would you use EAV for a new entity?**
+
+Using EAV for a new entity is advisable in case at least one of the following conditions is true:
+
+*   There is a scope.
+*   Admins and modules have the ability to add attributes into an entity or modify an attribute's `backend_type`.
+*   Potentially, the number of columns in the Flat model can exceed the maximum column per table limit (1017 with InnoDB).
+*   Potentially, the required amount of indexes, like INDEX in the Flat model, can exceed the maximum number of indexes per table (64 in InnoDB) or reach the amount when the entities' adding / modifying / deletion will be slow.
+
+![Magento Exam Information](./images/icon-info.png)Good to remember in general!
+
+![Magento Exam Question](./images/icon-question.png)**What are the pros and cons of EAV architecture?**
+
+![Magento Section Chevron](./images/icon-chevron.png) Advantages
+
+1.  The implementation of SCOPE in the Flat model stores a lot of unnecessary information. For example, if you want to redefine one attribute in another scope, then both EAV and Flat will create one line each. But in EAV, the number of columns is always fixed, while in Flat it can reach 1000. Additionally, there is a problem when the value is inherited from the parent scope. You can mark such values ​​as NULL, but then you must prevent the attributes from being NULL if they are not inherited.
+2.  Quickly add a new attribute. Adding a new attribute does not change the EAV table in any way. In Flat, you need to add a new column. The ALTER TABLE operation is also slow. This is especially noticeable in large tables.*
+3.  Changing `backend_type` attribute is faster. To change the attribute type in EAV, you need to move this attribute data from one table to another. For Flat, you need to perform ALTER TABLE.*
+4.  EAV allows us to separate attribute values ​​from entity field values.
+5.  The following InnoDB restrictions on the table restrict Flat:
+
+    *  The table may contain no more than 1017 columns
+    *  A table can contain a maximum of 64 indexes of type INDEX
+
+> `*` As for EAV, when adding / changing an attribute type, an ALTER TABLE is performed if the attribute's backend type is static.
+
+![Magento Section Chevron](./images/icon-chevron.png) Disadvantages
+
+1.  Getting entity attribute values ​​in EAV is slower than in Flat *
+2.  Search by attribute value in EAV is slower than in Flat *
+3.  In Flat, you can create an index on several attributes to speed up the search *
+
+* To speed up operations, some attributes can be set the `backend_type` as "static" and, if necessary, create indexes on the column with the attribute in the database, but then the visibility of the attribute will only be global. Another option is to use a flat table as an index if the data can be out of date.
+
+5.2 Demonstrate ability to use EAV entity load and save
+-------------------------------------------------------
+
+![Magento Exam Note Warning](images/icon-warning.png)Entity Manager
+
+> The `EntityManager` was introduced in Magento 2.1 . Since version 2.2 however, its use is not recommended by Magento anymore.
+>
+> Here is what the framework says about the class "`Magento\Framework\EntityManager\EntityManager`":
+>
+> "It is not recommended to use the EntityManager and its infrastructure for the Persistence Entities. In the next version a new "`PersistenceEntityManagerInterface`" will be created in order to cover the needs of the persistence with the API requests for the reading of the datas."
+>
+> Instead it is recommended to use the "`ResourceModel`" by inheriting from `Magento\Framework\Model\ResourceModel\Db\AbstractDb` or `Magento\Eav\Model\Entity\AbstractEntity` if it is an EAV model. For the collections and filters, it is recommended to use `Magento\Framework\Model\ResourceModel\Db\Collection\AbstractCollection`
+
+![Magento Section Chevron](./images/icon-chevron.png)Working Via EntityManager
+
+> If you want to work with `EntityManager` despite deprecation, you must provide information about the entity interface in `di.xml` for `MetadataPool` and for `HydratorPool`.
+>
+> Magento\Framework\EntityManager\OperationPool class contains operations array that call EntityManager for loading, saving, existence check and object deletion (C.R.U.D + check). The operation is performed by execute method.
+
+![Magento Exam Information](./images/icon-info.png)Remember Entity Manager uses C.R.U.D + a check methodology.
+```xml
+<type name="Magento\Framework\EntityManager\MetadataPool">
+   <arguments>
+       <argument name="metadata" xsi:type="array">
+           <item name="<MY>\<MODULE>\Api\Data\MyEntityInterface" xsi:type="array">
+               <item name="entityTableName" xsi:type="string">myvendor_mymodule_myentity_entity</item>
+               <item name="eavEntityType" xsi:type="string">myvendor_mymodule_myentity</item>
+               <item name="identifierField" xsi:type="string">entity_id</item>
+               <item name="entityContext" xsi:type="array">
+                   <item name="store" xsi:type="string">Magento\Store\Model\StoreScopeProvider</item>
+               </item>
+           </item>
+       </argument>
+   </arguments>
+</type>
+
+<type name="Magento\Framework\EntityManager\HydratorPool">
+   <arguments>
+       <argument name="hydrators" xsi:type="array">
+           <item name="<MY>\<MODULE>\Api\Data\MyEntityInterface" xsi:type="string">Magento\Framework\EntityManager\AbstractModelHydrator</item>
+       </argument>
+   </arguments>
+</type>
+```
+
+| Action | Class | Sub-operation |
+| --- | --- | --- |
+| `checkIfExists` | `Magento\Framework\EntityManager\Operation\CheckIfExists` | By default, CheckIfExists operation checks for the existence of an entry in the main table with a direct SQL query. |
+| `read` | `Magento\Framework\EntityManager\Operation\Read` | `ReadMain`, `ReadAttributes`, `ReadExtensions` |
+| `create` | `Magento\Framework\EntityManager\Operation\Create` | `CreateMain`, `CreateAttributes`, `CreateExtensions` |
+| `update` | `Magento\Framework\EntityManager\Operation\Update` | `UpdateMain`, `UpdateAttributes`, `UpdateExtensions` |
+| `delete` | `Magento\Framework\EntityManager\Operation\Delete` | `DeleteExtensions`, `DeleteAttributes`, `DeleteMain` |
+
+![Magento Exam Information](./images/icon-info.png)May not be necessary to remember since it's now deprecated. Again just remember Entity Manager uses C.R.U.D + a check methodology.
+
+![Magento Section Chevron](./images/icon-chevron.png)Attribute Operations
+
+> The EntityManager class relies on the OperationPool class Magento\Framework\EntityManager\OperationPool performing C.R.U.D operations on the entity itself. For instance, writing changes for an existing entity to the database (i.e. an update) is done using an operation subclass Magento\Framework\EntityManager\Operation\Update.
+>
+> Attribute Operations is responsible for performing C.R.U.D operations on attribute values into the new entities. Attribute Operations are located in the class Magento\Framework\EntityManager\Operation\AttributePool.
+>
+> This is defined in XML, and other modules can extend operations.
+
+![Magento Exam Information](./images/icon-info.png)The general `app/etc/di.xml` gives clues on how this works: Whenever OperationPool is instantiated, a type definition tells the Object Manager to instantiate the OperationPool with a list of operations.
+
+![Magento Section Chevron](./images/icon-chevron.png)Extensions Operations
+
+> Extensions Operations can be used to perform additional persistent operations on objects, like creating many-to-many relations, an example of this in 2.1 is the CMS module - to link the entity to the store.
+>
+> Extensions Operations are located in the class `Magento\Framework\EntityManager\Operation\ExtensionPool`.
+
+> Using overrides of Attributes Operations, EAV applies the following Handlers for operations:
+
+*   `Magento\Eav\Model\ResourceModel\CreateHandler` - Writes attribute values into the new entities. Creates, if the attribute is absent in Snapshot and the new value is not empty or the attribute allows empty values.
+*   `Magento\Eav\Model\ResourceModel\UpdateHandler` - takes a snapshot thanks to ReadSnapshot (which is based on ReadHandler). Then, UpdateHandler: Changes the value, if the attribute is modified relative to Snapshot and the new value is not empty or the attribute allows empty values. UpdateHandler Deletes, if the attribute is changed relative to Snapshot and the new value is empty and the attribute does not allow empty values.
+*   `Magento\Eav\Model\ResourceModel\ReadHandler` - ReadHandler performs reading by: Getting all attribute tables for a specific entity_type For each table, subquery attribute values for each scope then perform a UNION ALL of all subqueries writing resulting values are written into the $entityData array.
+
+![Magento Exam Question](./images/icon-question.png)**Describe the EAV load and save process and differences from the flat table load and save process.**
+
+![Magento Exam Information](./images/icon-info.png)Debatable whether or not the following question is still relevant any more since Flat catalog / categories are now not recommended.
+
+![Magento Section Chevron](./images/icon-chevron.png)Collections
+
+> EAV Collections derive from `Magento\Eav\Model\Entity\Collection\AbstractCollection` whereas Flat Collections derive from `Magento\Framework\Model\ResourceModel\Db\Collection\AbstractCollection`
+
+![Magento Section Chevron](./images/icon-chevron.png)Resource Models
+
+> EAV Resource Models extend `Magento\Eav\Model\Entity\AbstractEntity` and must implement the `getEntityType()` method, whereas Flat Resource Models extend `Magento\Framework\Model\ResourceModel\Db\AbstractDb` and initialize in the Magento constructor `_construct()` method.
+
+![Magento Section Chevron](./images/icon-chevron.png)Models
+
+> Both EAV Models extend `Magento\Framework\Model\AbstractModel` but EAV Models must establish the ENTITY constant whereas Flat Models do not.
+
+![Magento Section Chevron](./images/icon-chevron.png)Loading
+
+* `addAttributeToSelect()` converts attribute into its code and calls `addFieldToSelect()`
+* `addAttributeToFilter()` converts attribute into its code and calls `addFieldToFilter()`
+* `addAttributeToSort()` converts attribute into its code and calls `addOrder()`
+
+![Magento Section Chevron](./images/icon-chevron.png)Saving/Updating/Deleting
+
+* `Magento\Eav\Model\ResourceModel\CreateHandler` - To create values in new entities.
+* `Magento\Eav\Model\ResourceModel\UpdateHandler` - To modify / delete / add values into the existing entities.
+* `Magento\Eav\Model\ResourceModel\ReadHandler` - To get the values.
+
+![Magento Section Chevron](./images/icon-chevron.png)How to check for Flat Products
+
+`Magento\Catalog\Model\ResourceModel\Product\Collection`:
+
+```php
+if ($this->isEnabledFlat()) {
+  ...
+} else {
+  ...
+}
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)How to check for Flat Categories
+
+`Magento\Catalog\Model\Category` model is initialized the following way:
+```php
+protected function _construct()
+{
+    // If Flat Index enabled then use it but only on frontend
+    if ($this->flatState->isAvailable()) {
+        $this->_init(Magento\Catalog\Model\ResourceModel\Category\Flat::class);
+        $this->_useFlatResource = true;
+    } else {
+        $this->_init(Magento\Catalog\Model\ResourceModel\Category::class);
+    }
+}
+```
+![Magento Exam Question](./images/icon-question.png)**What happens when an EAV entity has too many attributes?**
+
+> The advantage of EAV, compared to Flat, is that the Flat table in InnoDb can not contain more than 1017 columns. In EAV, the number of attributes is limited by the maximum size of InnoDb tables - which is far greater (4 billion tables).
+>
+> Too many tables on disk will have no impact on MySQL (unless you have a filesystem that can't rapidly open a filename from a very full directory. As far as active tables however, those being used frequently in queries there are effects from:
+
+*   What queries you're running - although you aren't likely to be querying all tables within a single query.
+*   table_open_cache & innodb_open_files limits the number of tables cached. Exceeding these cache limits will cause tables to close and open and need to be re-examined adding overhead to queries.
+*   The overall query load on the system at any given point in time.
+
+![Magento Exam Question](./images/icon-question.png)**How does the number of websites/stores affect the EAV load/save process?**
+
+> The number of websites/stores impacts the entity loading / saving.
+> In Magento, scope in EAV is realized due to the "store_id" column in the EAV attribute value tables.
+
+*   store_id = 0, if scope global
+*   store_id = X of the selected Store View, if not global
+
+> Queries are loaded the following way:
+
+```sql
+SELECT XXX FROM <ENTITY_TABLE>_<`BACKEND_TYPE`> WHERE store_id IN (<STORE_IDS>)
+
+```
+
+> Where STORE_IDS are Store View identificators of the current context.
+>
+> The context is calculated recursively: In the STORE_IDS array, the identificator of the current scope is added. In case the current scope has Fallback scope, then an operation is repeated for Fallback.
+
+![Magento Exam Information](./images/icon-info.png)The more Store Views are in the Website, the more entries in the database you need to create or modify, and therefore the slower the loading/saving.
+
+![Magento Exam Information](./images/icon-info.png)It turns out that the number of websites / stores does not directly affect the upload speed, because when StoreScopeProvider is used during loading, the context contains no more than two store_id, i.e. does not depend on the number of websites / stores.
+
+![Magento Exam Question](./images/icon-question.png)**How would you customize the load and save process for an EAV entity in the situations described here?**
+
+![Magento Section Chevron](./images/icon-chevron.png)Overriding the operations
+
+`di.xml`:
+```xml
+<type name="Magento\Framework\EntityManager\OperationPool">
+   <arguments>
+       <argument name="operations" xsi:type="array">
+           <item name="<MY>\<MODULE>\Api\Data\MyEntityInterface" xsi:type="array">
+               <item name="checkIsExists" xsi:type="string">MY_NAMESPACE\CheckIsExists</item>
+               <item name="read" xsi:type="string">MY_NAMESPACE\Read</item>
+               <item name="create" xsi:type="string">MY_NAMESPACE\Create</item>
+               <item name="update" xsi:type="string">MY_NAMESPACE\Update</item>
+               <item name="delete" xsi:type="string">MY_NAMESPACE\Delete</item>
+           </item>
+       </argument>
+   </arguments>
+</type>
+```
+
+![Magento Exam Information](./images/icon-info.png)You can partially override, for example, a single "read" operation, then the default operations will be used for the rest of the operations.
+
+![Magento Section Chevron](./images/icon-chevron.png)Overriding the extensionActions
+
+`di.xml`:
+```xml
+<type name="Magento\Framework\EntityManager\Operation\ExtensionPool">
+   <arguments>
+       <argument name="extensionActions" xsi:type="array">
+           <item name="<MY>\<MODULE>\Api\Data\MyEntityInterface" xsi:type="array">
+               <item name="read" xsi:type="array">
+                   <item name="myReader" xsi:type="string">MY_NAMESPACE\ReadHandler</item>
+               </item>
+               <item name="create" xsi:type="array">
+                   <item name="myCreator" xsi:type="string">MY_NAMESPACE\CreateHandler</item>
+               </item>
+               <item name="update" xsi:type="array">
+                   <item name="myUpdater" xsi:type="string">MY_NAMESPACE\UpdateHandler</item>
+               </item>
+           </item>
+       </argument>
+   </arguments>
+</type>
+```
+
+5.3 Demonstrate ability to manage attributes
+--------------------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**Describe EAV attributes, including the frontend/source/backend structure.**
+
+> Backend Model: Performs loading, saving, deletion and validation of the attribute. Different validations are used based on the eav_attribute.`backend_type`.
+>
+> Source Model (`eav_attribute`.`source_model`): Provides a list of values for the attributes, which is later used for dropdown/multiselect attributes.
+>
+> Frontend (`eav_attribute`.`frontend_input`): How the Model displays the attribute at the frontend side e.g. "`select`".
+
+![Magento Exam Information](./images/icon-info.png)Similar things were mentioned in [Section 5.1](#h.7mu91scg3uyf) to help you remember.
+
+![Magento Exam Information](./images/icon-info.png)See Section [5.3 EAV Attribute Features](#h.v4fzn8rafjf4) for available types.
+
+![Magento Exam Question](./images/icon-question.png)**How would you add dropdown/multiselect attributes?**
+
+![Magento Section Chevron](./images/icon-chevron.png) Install Data Scripts
+
+> You can create attributes through the setup script (`Vendor\Module\Setup\InstallData` or `Vendor\Module\Setup\UpgradeData`).
+
+![Magento Section Chevron](./images/icon-chevron.png) Data patches
+
+![Magento Section Chevron](./images/icon-chevron.png)Admin
+
+> Via the admin panel (for products only).
+
+![Magento Section Chevron](./images/icon-chevron.png)Create new Extension Attribute
+
+Define a new [Extension Attribute](#h.2lcvcwr56aq) in [`<module_dir>/etc/extension_attributes.xml`](https://store.fooman.co.nz/blog/an-introduction-to-extension-attributes.html&sa=D&ust=1609223264976000&usg=AOvVaw2D54qlN24sv9fdXKR-CbVq) In the `<attribute>` field the `type=""` is your Backend Model and should point to your new Interface. Being a dropdown/multiselect this will need to be an array .i.e `ExampleAttributeInterface[]` - plural Interfaces.
+
+> Source Model (`eav_attribute`.`source_model`).
+>
+> Add a `backend_model`.
+>
+> Add a `frontend_model`.
+
+Example:
+
+```xml
+<extension_attributes for="Magento\Catalog\Api\Data\ProductInterface">
+   <attribute code="my_attribute" type="<MY>\<MODULE>\Api\Data\ExampleAttributeInterface[]" />
+</extension_attributes>
+```
+
+Interface (Service Contract):
+
+```php
+<?php
+
+namespace Vendor\MyModule\Api\Data;
+
+interface ExampleAttributeInterface
+{
+   const VALUE = 'example_attribute_code';
+
+   /**
+    * Return value.
+    *
+    * @return string|null
+    */
+   public function getValue();
+
+   /**
+    * Set value.
+    *
+    * @param string|null $value
+    * @return $this
+    */
+   public function setValue($value);
+}
+```
+Concrete Class (Implementation)
+```php
+<?php
+
+namespace Vendor\MyModule\Model;
+
+class ExampleAttribute implements \Vendor\MyModule\Api\Data\ExampleAttributeInterface
+{
+   /**
+    * {@inheritdoc}
+    */
+   public function getValue()
+   {
+       return $this->getData(self::VALUE);
+   }
+
+   /**
+    * {@inheritdoc}
+    */
+   public function setValue($value)
+   {
+       return $this->setData(self::VALUE, $value);
+   }
+}
+```
+
+Saving & Retrieving
+
+The use of plugins is the best approach here, in `di.xml`:
+```xml
+<type name="Magento\Catalog\Api\Data\ProductInterface">
+   <plugin name="save_example_attribute" type="Vendor\MyModule\Plugin\Data\ProductExampleAttributeExtensions" />
+</type>
+```
+
+Product Save
+```php
+<?php
+
+namespace Vendor\MyModule\Plugin;
+
+use Magento\Framework\Exception\CouldNotSaveException;
+
+class ProductExampleAttributeExtensions
+{
+    public function afterSave(
+        Magento\Catalog\Api\ProductRepositoryInterface $subject,
+        Magento\Catalog\Api\Data\ProductInterface $resultProduct
+    ) {
+        $resultOrder = $this->saveExampleAttribute($resultProduct);
+        return $resultProduct;
+    }
+
+    public function afterGet(
+        Magento\Catalog\Api\ProductRepositoryInterface $subject,
+        Magento\Catalog\Api\Data\ProductInterface $resultProduct
+
+    ) {
+
+        $resultProduct = $this->getExampleAttribute($resultProduct);
+        return $resultProduct;
+    }
+
+    private function getExampleAttribute(Magento\Catalog\Api\Data\ProductInterface $product)
+    {
+        try {
+            // The actual implementation of the repository is omitted
+            // but it is where you would load your value from the database (or any other persistent storage)
+            $exampleAttributeValue = $this->exampleRepository->get($product->getEntityId());
+        } catch (NoSuchEntityException $e) {
+            return $product;
+        }
+
+        $extensionAttributes = $product->getExtensionAttributes();
+        $productExtension = $extensionAttributes ? $extensionAttributes : $this->productExtensionFactory->create();
+        $exampleAttribute = $this->exampleAttributeFactory->create();
+        $exampleAttribute->setValue($exampleAttributeValue);
+        $productExtension->setExampleAttribute($exampleAttribute);
+        $product->setExtensionAttributes($productExtension);
+
+        return $product;
+    }
+
+    private function saveExampleAttribute(Magento\Sales\Api\Data\OrderInterface $product)
+    {
+        $extensionAttributes = $product->getExtensionAttributes();
+        if (
+            null !== $extensionAttributes && null !== $extensionAttributes->getExampleAttribute()
+        ) {
+            $exampleAttributeValue = $extensionAttributes->getExampleAttribute()->getValue();
+            try {
+                // The actual implementation of the repository is omitted
+                // but it is where you would save to the database (or any other persistent storage)
+                $this->exampleRepository->save($product->getEntityId(), $exampleAttributeValue);
+            } catch (\Exception $e) {
+                throw new CouldNotSaveException(
+                    __('Could not add attribute to order: "%1"', $e->getMessage()),
+                    $e
+                );
+            }
+        }
+        return $product;
+    }
+}
+
+```
+![Magento Exam Information](./images/icon-info.png)More info in [Section 4.1](#h.2lcvcwr56aq) to help you remember.
+
+![Magento Exam Question](./images/icon-question.png)**What other possibilities do you have when adding an attribute (to a product, for example)?**
+
+### ![Magento Section Chevron](./images/icon-chevron.png)EAV Attribute Features
+
+> EAV attribute has several features that we can specify. Class `Magento\Eav\Model\Entity\Setup\PropertyMapper` class contains the conversion of property names in the setup script into EAV attribute property in the database.
+
+| Feature in setup script | Feature in the database | Default value | Available Core Values |
+| --- | --- | --- | --- |
+| `attribute_model` | `attribute_model` | `null` | `Magento\Catalog\Model\ResourceModel\Eav\Attribute` |
+| `backend` | `backend_model` | `null` | `Magento\Catalog\Model\Attribute\Backend\Customlayoutupdate`, `Magento\Catalog\Model\Attribute\Backend\Startdate`, `Magento\Catalog\Model\Category\Attribute\Backend\Image`, `Magento\Catalog\Model\Category\Attribute\Backend\Sortby`, `Magento\Catalog\Model\Product\Attribute\Backend\Boolean`, `Magento\Catalog\Model\Product\Attribute\Backend\Category`, `Magento\Catalog\Model\Product\Attribute\Backend\Price`, `Magento\Catalog\Model\Product\Attribute\Backend\Sku`, `Magento\Catalog\Model\Product\Attribute\Backend\Stock`, `Magento\Catalog\Model\Product\Attribute\Backend\Tierprice`, `Magento\Catalog\Model\Product\Attribute\Backend\Weight`, `Magento\Customer\Model\Attribute\Backend\Data\Boolean`, `Magento\Customer\Model\Customer\Attribute\Backend\Billing`, `Magento\Customer\Model\Customer\Attribute\Backend\Password`, `Magento\Customer\Model\Customer\Attribute\Backend\Shipping`, `Magento\Customer\Model\Customer\Attribute\Backend\Store`, `Magento\Customer\Model\Customer\Attribute\Backend\Website`, `Magento\Customer\Model\ResourceModel\Address\Attribute\Backend\Region`, `Magento\Eav\Model\Entity\Attribute\Backend\ArrayBackend`, `Magento\Eav\Model\Entity\Attribute\Backend\Datetime`, `Magento\Eav\Model\Entity\Attribute\Backend\DefaultBackend` |
+| `type` | `backend_type` | `varchar` | `static`, `varchar`, `int`, `text`, `datetime`, `decimal` |
+| `table` | `backend_table` | `null` | `null` |
+| `frontend` | `frontend_model` | `null` | `Magento\Catalog\Model\Product\Attribute\Frontend\Image`, `Magento\Eav\Model\Entity\Attribute\Frontend\Datetime` |
+| `input` | `frontend_input` | `text` |  `boolean`, `select`, `text`, `image`, `media_image`, `price`, `date`, `textarea`, `gallery`, `multiselect`, `hidden`, `multiline` |
+| `label` | `frontend_label` | `null` | Any varchar up to 255 characters long |
+| `frontend_class` | `frontend_class` | `null` | `null` |
+| `source` | `source_model` | `null` | `Magento\Config\Model\Config\Source\Locale\Currency\All`, `Magento\Config\Model\Config\Source\Locale\Country`, `Magento\Config\Model\Config\Source\Locale\Timezone`, `Magento\Config\Model\Config\Source\Locale\Weekdaycodes`, `Magento\Config\Model\Config\Source\Locale\Weekdays`, `Magento\Config\Model\Config\Source\Locale\Currency`, `Magento\Config\Model\Config\Source\Email\Identity`, `Magento\Config\Model\Config\Source\Email\Method`, `Magento\Config\Model\Config\Source\Email\Template`, `Magento\Config\Model\Config\Source\Email\Smtpauth`, `Magento\Config\Model\Config\Source\Reports\Scope`, `Magento\Config\Model\Config\Source\Store`, `Magento\Config\Model\Config\Source\Dev\Dbautoup`, `Magento\Config\Model\Config\Source\Design\Robots`, `Magento\Config\Model\Config\Source\Yesnocustom`, `Magento\Config\Model\Config\Source\Web\Protocol`, `Magento\Config\Model\Config\Source\Web\Redirect`, `Magento\Config\Model\Config\Source\Website\AdminOptionHash`, `Magento\Config\Model\Config\Source\Website\OptionHash`, `Magento\Config\Model\Config\Source\Locale`, `Magento\Config\Model\Config\Source\Enabledisable`, `Magento\Config\Model\Config\Source\Yesno`, `Magento\Config\Model\Config\Source\Date\Short`, `Magento\Config\Model\Config\Source\Nooptreq`, `Magento\Config\Model\Config\Source\Image\Adapter`, `Magento\Config\Model\Config\Source\Admin\Page`, `Magento\Config\Model\Config\Source\Website` |
+| `required` | `is_required` | `1` | `1` & `0` |
+| `user_defined` | `is_user_defined` | `0` | `1` & `0` |
+| `default` | `default_value` | `null` | `null` |
+| `unique` | `is_unique` | `0` | `1` & `0` |
+| `note` | `note` | `null` | `null` |
+| `global` | `is_global` | `0` | `Magento\Eav\Model\Entity\Attribute\ScopedAttributeInterface::SCOPE_STORE` (0), `Magento\Eav\Model\Entity\Attribute\ScopedAttributeInterface::SCOPE_GLOBAL` (1), `Magento\Eav\Model\Entity\Attribute\ScopedAttributeInterface::SCOPE_WEBSITE` (2) |
+| `sort_order` | `sort_order` | `null` | `null` |
+| `group` | `group` | `General` | e.g. `General`, `Search Engine Optimization`, `Display Settings` |
+
+![Magento Exam Information](./images/icon-info.png)You can also specify:
+
+*   `option` – the list of values for dropdown/multiselect attributes
+
+![Magento Exam Information](./images/icon-info.png)You can find `backend_type`, type, frontend_input and input values from your database's eav_attribute table. You can check for `backend_type` value for your type case and frontend_input for your input value for all attributes from this table.
+
+![Magento Section Chevron](./images/icon-chevron.png)EAV Attribute Magento/Catalog Additional Features
+
+Additionally, Magento/Catalog has the following properties according to Magento\Catalog\Model\ResourceModel\Setup\PropertyMapper:
+
+| Feature in setup script | Feature in the database | Default value |
+| --- | --- | --- |
+| `input_renderer` | `frontend_input_renderer` | `null` |
+| `visible` | `is_visible` | `1` |
+| `searchable` | `is_searchable` | `0` |
+| `filterable` | `is_filterable` | `0` |
+| `comparable` | `is_comparable` | `0` |
+| `visible_on_front` | `is_visible_on_front` | `0` |
+| `wysiwyg_enabled` | `is_wysiwyg_enabled` | `0` |
+| `is_html_allowed_on_front` | `is_html_allowed_on_front` | `0` |
+| `visible_in_advanced_search` | `is_visible_in_advanced_search` | `0` |
+| `filterable_in_search` | `is_filterable_in_search` | `0` |
+| `used_in_product_listing` | `used_in_product_listing` | `0` |
+| `used_for_sort_by` | `used_for_sort_by` | `0` |
+| `apply_to` | `apply_to` | `null` |
+| `position` | `position` | `0` |
+| `used_for_promo_rules` | `is_used_for_promo_rules` | `0` |
+| `is_used_in_grid` | `is_used_in_grid` | `0` |
+| `is_visible_in_grid` | `is_visible_in_grid` | `0` |
+| `is_filterable_in_grid` | `is_filterable_in_grid` | `0` |
+| `attribute_set` | `attribute_set` | `null` (Accepts strings such as "Default") |
+
+![Magento Exam Question](./images/icon-question.png)**Describe how to implement the interface for attribute frontend models. What is the purpose of this interface? How can you render your attribute value on the frontend?**
+
+![Magento Section Chevron](./images/icon-chevron.png)How
+
+> To create Frontend model, create a class, inherited from `Magento\Eav\Model\Entity\Attribute\Frontend\AbstractFrontend`, and override getValue method.Then, set frontend_model as the name of the newly created class.
+```PHP
+class TestFrontend extends \Magento\Eav\Model\Entity\Attribute\Frontend\AbstractFrontend
+{
+    public function getValue(Magento\Framework\DataObject $object)
+    {
+        $attribute_code = $this->getAttribute()->getAttributeCode();
+        $value = $object->getData($attribute_code);
+        return nl2br(htmlspecialchars($value));
+    }
+}
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)Why (purpose).
+
+> The purpose of the interface is to decrease the code dependency (dependency inversion principle).
+
+![Magento Exam Question](./images/icon-question.png)**Identify the purpose and describe how to implement the interface for attribute source models.**
+
+> The model is used for providing a list of attribute values for dropdown/multiselect attributes. Source model realization example:
+
+```PHP
+class TestSource extends \Magento\Eav\Model\Entity\Attribute\Source\AbstractSource
+{
+    public function getAllOptions()
+    {
+        if (!$this->_options) {
+            $this->_options = [
+                ['label' => __('Label 1'), 'value' => 'value 1'],
+                ['label' => __('Label 2'), 'value' => 'value 2'],
+                ['label' => __('Label 3'), 'value' => 'value 3'],
+                ['label' => __('Label 4'), 'value' => 'value 4']
+            ];
+        }
+
+        return $this->_options;
+    }
+}
+```
+![Magento Exam Question](./images/icon-question.png)**For a given dropdown/multiselect attribute, how can you specify and manipulate its list of options?**
+
+> The values are stored in the eav_attribute_option_value table. If the source_model is the `Magento\Eav\Model\Entity\Attribute\Source\Table` class or is inherited from it. The values can be added when creating an attribute in the option property, or you can call the `Magento\Eav\Setup\EavSetup->addAttributeOption($option)` method.
+>
+> If the source model is not inherited from `Magento\Eav\Model\Entity\Attribute\Source\Table`, then, to change the list of values, you can:
+
+*   Create a plugin on the source model on the `getAllOptions` method
+*   Create a new source model, inherited from the mutable class, change the behavior of the `getAllOptions` method and specify the new `source_model` in the attributes
+
+![Magento Exam Information](./images/icon-info.png)Just remember that The values are stored in the eav_attribute_option_value table and that the `source_model` column should reference a class inherited from `Magento\Eav\Model\Entity\Attribute\Source\Table` which allows you to override the `addAttributeOption` method.
+
+![Magento Exam Question](./images/icon-question.png)**Identify the purpose and describe how to implement the interface for attribute backend models.**
+
+> Backend modules are created with a purpose to upload / save / delete / validate attribute values.
+
+![Magento Section Chevron](./images/icon-chevron.png)How
+
+`<module_dir>etc\adminhtml\system.xml`
+```xml
+<field id="config_example" translate="label" type="obscure" sortOrder="40" showInDefault="1" showInWebsite="1">
+    <label>API Password</label>
+    <config_path>my_module/section/config_example</config_path>
+    <backend_model>Vendor\MyModule\Model\Config\Backend\TestBackend</backend_model>
+    <attribute type="shared">1</attribute>
+</field>
+```
+
+```php
+class TestBackend implements Magento\Framework\App\Config\ValueInterface
+{
+    public function isValueChanged($object)
+    {
+    }
+
+    Public function getOldValue()
+    {
+    }
+
+    public function getFieldsetDataValue($key)
+    {
+    }
+}
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)How (and why) would you create a backend model for an attribute?
+
+> Backend modules are created with a purpose to upload / save / delete / validate attribute values.
+
+![Magento Exam Question](./images/icon-question.png)**Describe how to create and customize attributes. How would you add a new attribute to the product, category, or customer entities? What is the difference between adding a new attribute and modifying an existing one?**
+
+![Magento Section Chevron](./images/icon-chevron.png)Adding a new attribute
+
+Data patches are used for creating a new attribute using the injected method:
+
+```php
+Magento\Eav\Setup\EavSetupFactory->create()->addAttribute(string $entityType, string $attributeCode, array $properties)
+```
+
+*   For Products use entity code `Magento\Catalog\Model\Product::ENTITY`
+*   For Inventory use entity code `Magento\CatalogInventory\Model\Stock::ENTITY`
+*   For Stock Items use entity code `Magento\CatalogInventory\Model\Stock\Item::ENTITY`
+*   For Categories use entity code `Magento\Catalog\Model\Category::ENTITY`
+*   For Customers use entity code `Magento\Customer\Model\Customer::ENTITY`
+*   For Customer Groups use entity code `Magento\Customer\ModelGroup::ENTITY`
+*   For Customer Address use entity code `Magento\Customer\Model\Indexer\Address\AttributeProvider::ENTITY`
+
+[More info on Data Patches in Section 4.2](#h.8i0etxv2dw9i)
+
+![Magento Exam Information](./images/icon-info.png)For products you can also [manually create attributes via the admin](https://docs.magento.com/user-guide/stores/attributes-product.html&sa=D&ust=1609223265035000&usg=AOvVaw0p75AzVbovNy8DnDVQaMh8) in Stores > Attributes > Product
+
+![Magento Exam Information](./images/icon-info.png)For customers you can also [manually create attributes via the admin](https://docs.magento.com/user-guide/stores/attributes-customer.html&sa=D&ust=1609223265035000&usg=AOvVaw31283qtMpVdnNfLYT466ui) in Stores > Attributes > Customer (Magento Enterprise Commerce feature only).
+
+![Magento Exam Note Warning](images/icon-warning.png)Setup scripts are applied to create or modify an attributes, however this has become deprecated as of Magento 2.3
+
+![Magento Section Chevron](./images/icon-chevron.png)Modifying an existing attribute
+
+> Much like creating an attribute (above), use a Data Patch with the same injected class:
+
+```php
+Magento\Eav\Setup\EavSetupFactory->create()->updateAttribute(string $entityType, string $attributeCode, string $attributeField, mixed $value = null, int $sortOrder = null);
+```
+[More info on Data Patches in Section 4.2](#h.8i0etxv2dw9i)
+
+![Magento Exam Information](./images/icon-info.png)For customers you can also [manually modify most attributes via the admin](https://docs.magento.com/user-guide/stores/attributes-customer.html&sa=D&ust=1609223265037000&usg=AOvVaw3nuq9nltxOteADYAxh-H1F) in Stores > Attributes > Customer (Magento Enterprise Commerce feature only). However, properties such as: frontend_class & attribute_code ARE NOT editable after creation.
+
+![Magento Exam Information](./images/icon-info.png)For products you can [manually modfiy most attributes via the admin](https://docs.magento.com/user-guide/stores/attributes-product.html&sa=D&ust=1609223265037000&usg=AOvVaw2yFkHEc2Lva4xKVBXLJ5xL) in Stores > Attributes > Product. However, properties such as: input_type, attribute_code, sort_order, used_in_forms ARE NOT editable after creation.
+
+![Magento Exam Note Warning](images/icon-warning.png)Setup scripts are applied to create or modify an attributes, however this has become deprecated as of Magento 2.3
\ No newline at end of file
diff --git a/6. Developing with Adminhtml/1. Describe common structure architecture.md b/6. Developing with Adminhtml/1. Describe common structure architecture.md
deleted file mode 100644
index a914d26..0000000
--- a/6. Developing with Adminhtml/1. Describe common structure architecture.md	
+++ /dev/null
@@ -1,146 +0,0 @@
-# Describe common structure/architecture
-
-## Some URLs in backend start with "admin/admin/.." - 2 times admin, some only 1 - "admin/...". How?
-
-Sample router:
-```xml
-<router id="admin">
-    <route id="adminhtml"> <!-- frontName="admin" -->
-        <module name="Magento_Theme" />
-    </route>
-    <route id="theme" frontName="theme">
-        <module name="Magento_Theme" />
-    </route>
-</router>
-```
-
-Sample menu items:
-- menu add action="adminhtml/system_design_theme"
-    http://example.com/admin/admin/system_design_theme/index/key/$secret/
-    \Magento\Theme\Controller\Adminhtml\System\Design\Theme\Index
-    * /admin/admin/system_design_theme/index
-    * App\AreaList.getCodeByFrontName('admin')
-    * \Magento\Backend\App\Area\FrontNameResolver::getFrontName
-    * default front name = deployment config `backend/frontName` - from env.php
-    * if config `admin/url/use_custom_path`, admin front name = config `admin/url/custom_path`
-
-- menu add action="theme/design_config"
-    http://example.com/admin/theme/design_config/index/key/$secret/
-    \Magento\Theme\Controller\Adminhtml\Design\Config\Index
-
-Fun fact: same "Content > Design > Themes" link can open by 2 different URLs:
-- http://example.com/admin/admin/system_design_theme/index/key/82c8...6bfa/
-- http://example.com/admin/theme/system_design_theme/index/key/0ed6...6c75/
-
-First link "hides" behind Magento_Backend original route "adminhtml"="admin" frontName.
-Second link has own frontName="theme" and is more beautiful.
-
-
-Admin app flow:
-- bootstrap.run(application)
-- application.launch
-- front controller.dispatch
-- admin routerList:
-  * `admin`
-  * `default`
-- Magento\Backend\App\Router.match - same as frontend, but admin parses *4* sections:
-  * parseRequest
-    + `_requiredParams = ['areaFrontName', 'moduleFrontName', 'actionPath', 'actionName']`
-    + "admin/admin/system_design_theme/index"
-
-`router id="admin"`
-
-Admin router - Base, same as frontend, BUT:
-- `_requiredParams = ['areaFrontName', 'moduleFrontName', 'actionPath', 'actionName']` - *4* sections, rest is params.
-    Example: "kontrollpanel/theme/design_config/index/key/3dd89..7f6e/":
-    * moduleFrontName = "theme", actionPath = "design_config", actionName = "index",
-    * parameters = [key: 3dd89..7f6e]
-    * fromt name "theme" - search adminhtml/routers.xml for ....?
-    Example 2 "/kontrollpanel/admin/system_design_theme/index/key/4bd2...13/:
-    * moduleFrontName = "admin", actionPath = "system_design_theme", actionName = "index"
-    * parameters = [key: 4bd2...13]
-    
-- `pathPrefix = 'adminhtml'` -- all controller classes are searched in `Module\Controller\Adminhtml\...`
-
-When in *adminhtml area*, ALL controllers will reside in Controller/Adminhtml/ modules path.
-
-Module_Backend registers router `<route name="adminhtml" frontName="admin">` => `<module name="Magento_Backend"/>`.
-This means that `getUrl("adminhtml/controller/action")`:
-- Magento\Backend\Model\Url adds prefix `$areaFrontName/` in `_getActionPath`
-- *route name* "adminhtml", frontName will always be "admin/"
-- default controllers search module is *Magento_Backend*
-- declaring other modules before "Magento_Backend" you risk overriding some system backend controllers:
-  + ajax/translate, auth/login, dashboard/index, index/index, system/store etc.
-
-You can in turn *register own router* `<route name="theme" frontName="theme">` => `<module name="Module_Alias"/>`.
-You will generate links with `getUrl("theme/controller/action")`:
-- backend URL model._getActionPath adds prefix areaFrontName
-- *route name* "theme", frontName "theme"
-- controlles are searched *only in your module* Module_Alias, no interference with Magento_Backend controllers.
-
-### What does `router id="admin"`, `router id="standard"` mean in routes.xml?
-```xml
-<config>
-    <router id="admin">
-        <routes>
-            <route name="adminhtml" frontName="admin">...</route>
-        </routes>
-    </router>
-    <router id="standard">
-        <routes>
-            <route name="checkout" frontName="checkout">...</route>
-        </routes>
-    </router>
-</config>
-```
-We know that frontend and admin areas main *router* is almost the same - \Magento\Framework\App\Router\Base.
-It simply finds *routes* by matching `frontName`.
-
-Key difference is matched *area* in *area list* defined `router` name:
-- `adminhtml` area - `admin` *router*.
-- `frontend` area - `standard` *router*.
-All routes and frontNames are read only from router by ID.
-
-This means that admin routes always lie in etc/adminhtml/routes.xml and have `router id="admin"`.
-Frontend routes - etc/frontend/routes.xml and always have `router id="standard"`.
-This looks like redundancy to me.
-
-*Admin controller load summary (one more time)*:
-- match backend route name
-- match adminhtml area, router = 'admin'
-- load adminhtml configuration
-- adminhtml/di.xml - routerList = [admin, default]
-- admin router = extends frontend Base router
-- parse params - 4 parts: [front area from env.php, frontName, controllerPath, actionName]
-- search routes.xml/router id="admin"/route by frontName=$frontName - second parameter
-- matched route has 1+ ordered module names, e.g. [Module_Theme, Module_Backend]
-- search controller class in each Module_Name/Controller/Adminhtml/[Controller/Path]/[ActionName]
-
-
-*URL generation*:
-
-In *frontend* URLs are generated with `\Magento\Framework\Url.getUrl`:
-- getUrl() -> createUrl() = getRouterUrl + ?query + #fragment
-- getRouterUrl() = getBaseUrl() + `_getRoutePath`
-- getBaseUrl() example 'http://www.example.com/'
-- `_getRoutePath` = `_getActionPath` + params pairs. For example: 'catalog/product/view/id/47'
-- `_getActionPath` example: 'catalog/product/view'
-
-In *backend* use customized version `\Magento\Backend\Model\Url`:
-- `_getActionPath` *prepends* area front name, e.g. 'kontrollpanel/catalog/product/view'.
-  Now all backend links have this prefix.
-- getUrl() adds secret key /key/hash
-- can disable secret key generation with turnOffSecretKey() and revert with turnOnSecretKey().
-  Global admin config `admin/security/use_form_key`.
-
-*Secret key* = `hash($routeName . $controllerName . $actionName . $sessionFormKey)`
-
-
-
-
-## Describe the difference between Adminhtml and frontend. What additional tools and requirements exist in the admin?
-- ACL permissions - `_isAllowed`, change static const `ADMIN_RESOURCE`
-- base controller Magento\Backend\App\Action = Magento\Backend\App\AbstractAction
-- custom *URL model* - secret key `key`
-- layout `acl` block attribute
-- ...
diff --git a/6. Developing with Adminhtml/2. Define form and grid widgets.md b/6. Developing with Adminhtml/2. Define form and grid widgets.md
deleted file mode 100644
index a3a863b..0000000
--- a/6. Developing with Adminhtml/2. Define form and grid widgets.md	
+++ /dev/null
@@ -1,493 +0,0 @@
-# Define form and grid widgets
-
-## UI Component generation
-
-UI component scheme - `urn:magento:module:Magento_Ui:etc/ui_configuration.xsd`
-Magento_Ui, name just like page_configuration
-
-Generation flow:
-- \Magento\Framework\View\Layout\Generator\UiComponent::generateComponent - create, prepare, wrap
-- create component \Magento\Framework\View\Element\UiComponentFactory::create
-  * \Magento\Framework\View\Element\UiComponentFactory::mergeMetadata -- components definitions in array format + dataProvider.getMeta
-    + metadata = ['cert_form' => ['children' => dataProvider.getMeta]]
-  * for each child[], \Magento\Framework\View\Element\UiComponentFactory::createChildComponent recursively:
-    + create PHP class for component, e.g. `new Magento\Ui\Component\DataSource($components = [])`;
-  * create PHP class for component, e.g. `new Magento\Ui\Component\Form($components = [children...])`;
-- prepare component recursively
-  * getChildComponents[].prepare - update data, js_config etc.
-- wrap to *UiComponent\Container* as child 'component'
-  * toHtml = render -> renderEngine->render (template + '.xhtml')
-
-## AbstractComponent
-
-*component PHP class common arguments:*
-- name
-- template -> .xhtml
-- layout: generic - default/tabs. DI config Magento\Framework\View\Layout\Pool
-- config:
-  * value
-- js_config:
-  * component - JS component class
-  * extends - by default context.getNamespace - top level UI component instance name, e.g. 'cms_block_form'
-  * provider - context.addComponentDefinition - adds to "types"
-- actions - context.addActions. Broken?
-- html_blocks - context.addHtmlBlocks
-- buttons - context.addButtons
-- observers
-
-*What is the difference between component data `config`, `js_config` and others?*
-- looks like js_config is special - goes to `types` definition
-- config - normal JS component config overriding `defaults`?
-- other values - only for PHP component class usage?
-
-#### `provider`, `extends`
-- PHP Component.getJsConfig - all components automatically get `data.js_config.extends = [top level ui component name]`.
-- PHP Component.`prepare`:
-  * every component data.js_config is registered in `types` by constant type (_see below_).
-    Definitions for multiple same types (component `column` occurres many times) are merged.
-  * when data.js_config.`provider` is set:
-    + `extends` is removed. This is TOP LEVEL component.
-    + this TOP LEVEL compoment data.js_config is registered by personal name - e.g. "cms_block_form" instead of "form".
-
-This makes sense - ALL components inherit same top level `provider` via `extends`.
-
-Example:
-```
-"Magento_Ui/js/core/app": {
-    "types": {
-        // [component constant type]: [data.js_config],
-        // TOP LEVEL specific js_config and required provider
-        cms_block_form: {
-            provider: 'cms_block_form_data_source'
-        },
-        // below are generic types by constant type
-        form: {
-            extends: 'cms_block_form'
-        },
-        fieldset: {
-            component: 'Magento_Ui/js/form/components/fieldset',
-            extends: 'cms_block_form'
-        },
-        input: {
-            extends: 'cms_block_form'
-        }
-
-    },
-    "components": ...
-}
-```
-
-## DataSource, DataProvider
-
-DataProvider interface is NOT in UI module, but in framework.
-Magento\Framework\View\Element\Uicomponent\DataProvider\DataProviderInterface:
-- getName - why???
-- getData - [items, totalItems]
-- setConfig, getConfigData
-- addFilter, addOrder, setLimit
-- getPrimaryFieldName - used e.g. to delete row by ID
-- getRequestFieldName ???
-- getMeta -- extends/overrides ui component structure - converted array.
-  Meta format example: 
-
-     ```
-      [
-          '' => [
-              attributes => [
-                  class => 'Magento\Ui\Component\Form',
-                  name => 'some_name',
-              ],
-              arguments => [
-                  data => [
-                      js_config => [
-                          component => 'Magento_Ui/js/form/form',
-                          provider => 'cms_block_form.block_form_data_source',
-                      ],
-                      template => 'templates/form/collapsible',
-                  ],
-              ],
-              children => [ ...nested components... ]
-          ]
-      ]
-    ```
-- getFieldMetaInfo, getFieldsMetaInfo, getFieldsetMetaInfo -- wtf?
-- getSearchCriteria, getSearchResult ???
-
-You don't have to implement data provider from scratch, choose from 2 implementations:
-- in framework next to interface - `Magento\Framework\View\Element\UiComponent\DataProvider\DataProvider`.
-    This provider sets collects all input filters and sorts into *search criteria*.
-    Data is returned like `searchResult = $this->reporting->search($searchCriteria)`. Nice and tidy.
-  * static properties are passed in ui component XML in `listing/dataSource/dataProvider/settings`:
-    + name ??? - `[YourComponentName]_data_source`
-    + primaryFieldName, e.g. `entity_id`
-    + requestFieldName, e.g. `id`
-  * addFilter, addOrder, setLimit - proxy to search criteria builder
-  
-  But who will process our searchCriteria?
-  * `\Magento\Framework\View\Element\UiComponent\DataProvider\Reporting` is responsible for
-    returning SearchResult by SearchCriteria.
-  * `\Magento\Framework\View\Element\UiComponent\DataProvider\CollectionFactory` creates collection
-    instance by *data provider name*.
-  * You register your collection as DI arguments for CollectionFactory:
-    ```xml
-    <type name="Magento\Framework\View\Element\UiComponent\DataProvider\CollectionFactory">
-        <arguments>
-            <argument name="collections" xsi:type="array">
-                <item name="sales_order_grid_data_source" xsi:type="string">Magento\Sales\Model\ResourceModel\Order\Grid\Collection</item>
-            </argument>
-        <arguments>
-    </type>
-    ```
-
-- in Magento_Ui - `\Magento\Ui\DataProvider\AbstractDataProvider`
-    This provider works directly with *collection*, you define collection in constructor when extending.
-  * as usual, static properties are passed in ui component XML as arguments or settings:
-    + name
-    + primaryFieldName
-    + requestFieldName
-    + meta
-    + data - data['config'] for your own usage, you can pass some settings, preferences etc.
-  * addFilter = collection.addFieldToFilter
-  * addOrder = collection.addOrder
-  * etc...
-  * getData = collection.toArray
-
-
-## Source of confusion - unknown UI component.xml structure, node names. `definition.map.xml`
-
-`definition.map.xml` maps what values come from where! This explains custom node names and attributes that are
-magically inserted in resulting JS configuration.
-
-`Magento_Ui/view/base/ui_component/etc/definition.map.xml`
-
-E.g. component `dataSource` > argument `dataProvider` -> primaryFieldName = `xpath(dataProvider/settings/requestFieldName)`
-Example from `definition.map.xml`:
-
-```xml
-    <component name="dataSource">
-        <schema name="current">
-            <argument name="dataProvider" xsi:type="configurableObject">
-                <argument name="data" xsi:type="array">
-                    <item name="config" xsi:type="array">
-                        <item name="submit_url" type="url" xsi:type="converter">settings/submitUrl</item>
-                        ...
-                        <item name="clientConfig" type="item" xsi:type="converter">dataProvider/settings/clientConfig</item>
-                        <item name="provider" type="string" xsi:type="xpath">@provider</item>
-                        ...
-                    </item>
-                    <item name="js_config" xsi:type="array">
-                        <item name="deps" type="deps" xsi:type="converter">settings/deps</item>
-                    </item>
-                    <item name="layout" xsi:type="array">
-                        <item name="type" type="string" xsi:type="xpath">settings/layout/type</item>
-                        <item name="navContainerName" type="string" xsi:type="xpath">settings/layout/navContainerName</item>
-                    </item>
-                </argument>
-                <argument name="class" type="string" xsi:type="xpath">dataProvider/@class</argument>
-                <argument name="name" type="string" xsi:type="xpath">dataProvider/@name</argument>
-    ...
-```
-And `definition.xml`:
-```xml
-<dataSource class="Magento\Ui\Component\DataSource"/>
-```
-
-Using definition.map.xml we can deduce full `<dataSource>` definition and what parameter will end up where:
-```xml
-<dataSource class="Magento\Ui\Component\DataSource">
-    <aclResource/>
-    <settings>
-        <submitUrl />
-        <validateUrl />
-        <updateUrl/>
-        <filterUrlParams/>
-        <storageConfig/>
-        <statefull/>
-        <imports/>
-        <exports/>
-        <links/>
-        <listens/>
-        <ns/>
-        <componentType/>
-        <dataScope/>
-        <deps/>
-        <layout>
-            <type/>
-            <navContainerName/>
-        </layout>
-    </settings>
-    <dataProvider name="some_name" class="SomeDataProviderClass">
-        <settings>
-            <primaryFieldName>entity_id</primaryFieldName>
-            <requestFieldName>id</requestFieldName>
-        </settings>
-    </dataProvider>
-</dataSource
-```
-
-Fun fact - some parameters are scattered in `settings`, another in `dataProvider/settings`, but in fact ALL
-of them will be used only for dataProvider object data.
-
-PHP data source creation equivalent:
-```php
-$dataProvider = $objectManager->create(`SomeDataProviderClass`, [
-    'name' => 'some_name',
-    'primaryFieldName' => 'entity_id',
-    'requestFieldName' => 'id',
-    'data' => [
-        'config' => [
-            'submit_url' => '',
-            'validate_url' => '',
-            'update_url' => '',
-            'filter_url_params' => '',
-            'clientConfig' => '',
-            'provider' => '',
-            'component' => '',
-            'template' => '',
-            'sortOrder' => '',
-            'displayArea' => '',
-            'storageConfig' => '',
-            'statefull' => '',
-            'imports' => '',
-            'exports' => '',
-            'links' => '',
-            'listens' => '',
-            'ns' => '',
-            'componentType' => '',
-            'dataScope' => '',
-            'aclResource' => '',
-        ],
-        'js_config' => [
-            'deps' => [],
-        ],
-        'layout' => [
-            'type' => '',
-            'navContainerName' => '',
-        ],
-    ],
-]);
-$dataSource = $objectManager->create('Magento\Ui\Component\DataSource', [
-  'dataProvider' => $dataProvider,
-]);
-```
-
-With this sacred knowledge we can add/override data provider parameters explicitly in addition to normal config:
-```xml
-<dataSource name="...">
-    <argument name="dataProvider" xsi:type="configurableObject">
-        <argument name="data" xsi:type="array">
-            <item name="config" xsi:type="array">
-                <item name="referer_url" xsi:type="url" path="sales/archive/shipments/index"/>
-            </item>
-        </argument>
-    </argument>
-    <dataProvider class="..." name="..">
-        <settings>...</settings>
-    </dataProvider>
-</dataSource>
-```
-
-Okay, ui component *data source* doesn't get any configuration, it all goes to *data provider* - 'submit_url' etc.
-Data provider can only return data and modify meta, how does it pass these JS values for JS components?
-
-Here's how:
-- View\Layout\Generic::build (initial page open) or
-  View\Element\UiComponent\ContentType\Json::render (load AJAX data)
-- context.getDataSourceData -- merges
-  * component.getDataSourceData
-  * data provider.getConfigData -- returns data['config'] -- all the params we set as arguments
-
-
-## UI Form
-
-*Caveats:*
-- default form data.template is `templates/form/default`. But its spinner works only with `tabs` layout.
-  `<div data-role="spinner" data-component="{{getName()}}.areas"`. Normal form does not have `areas`, and
-  so this spinner will work forever.
-  Solution:
-  * either set arguments.data.template = `templates/form/collapsible`:
-    `<div data-role="spinner" data-component="{{getName()}}.{{getName()}}"` - this matches normal form
-  * or set form.settings.layout.type = `tabs`. It will init `areas` suitable for default template.
-    See \Magento\Ui\Component\Layout\Tabs::initAreas.
-
-*component Form.getDataSourceData*:
-- read ID from request, e.g. current entity ID
-- filter data provider by primaryField = $requestedValue
-- get row data by requested primary ID
-  * note that normal collections don't return rows indexed by ID and you will receive an error
-  * Magento data provider override getData and index by ID manually, e.g. \Magento\Cms\Model\Page\DataProvider::getData
-
-### *Working with form fields*:
-
-Example: `<field name="something" formElement="input">`.
-
-Magic unraveled:
-- see definition.xml `<field class="Magento\Ui\Component\Form\Field"/>`
-- \Magento\Ui\Component\Form\Field::prepare - creates new child ui component `wrappedComponent`
-  with type = `$this->getData('config/formElement')`.
-- how to set config/formElement? See definition.map.xml, search for `component name="field"`:
-    `<item name="formElement" type="string" xsi:type="xpath">@formElement</item>`.
-
-`formElement` creates arbitrary ui component and inherits same data as main `field`.
-
-*Suitable `formElement` types:*
-- input
-- textarea
-- fileUploader
-- date
-- email
-- wysiwyg
-- checkbox, prefer radio/toggle
-    ```xml
-    <formElements>
-        <checkbox>
-            <settings>
-                <valueMap>
-                    <map name="false" xsi:type="number">0</map>
-                    <map name="true" xsi:type="number">1</map>
-                </valueMap>
-                <prefer>toggle</prefer>
-            </settings>
-        </checkbox>
-    </formElements>
-    ```
-- select:
-    ```xml
-    <formElements>
-        <select>
-            <settings>
-                <options class="Magento\Config\Model\Config\Source\Design\Robots"/>
-            </settings>
-        </select>
-    </formElements>
-    ```
-- multiselect
-
-
-## UI Listing
-`listing` structure:
-- argument data.js_config.provider
-- `dataSource`
-  * `dataProvider`
-- `filterbar`
-  * `filters`
-  * `bookmark`
-  * `export`
-  * `massaction`
-- `columns`
-  * `column`
-
-
-- `listing` - just container, server template 'templates/listing/default.xhtml'
-- `columns` - no server processing, all juice here:
-  * JS component Magento_Ui/js/grid/listing
-- `column`
-  * JS component Magento_Ui/js/grid/columns/column
-  * don't forget to include config/dataType = settings/dataType
-
-
-Implementing listing checklist:
-- set settings/spinner = "columns"
-  * Listing template 'templates/listing/default.xhtml' has spiner `data-component="{{getName()}}.{{getName()}}.{{spinner}}"`
-  * `columns` js component - `Magento_Ui/js/grid/listnig` - hides data when loaded - `loader.get(this.name).hide()`.
-- dataSource must specify provider in order to load data propertly
-  `<dataSource provider="Magento_Ui/js/grid/provider"/>`
-  This provider handles loading data via AJAX.
-- set `dataSource/settings/updateUrl` = `mui/index/render`. This will return grid data in JSON format.
-  When this parameter is missing, AJAX is made to current URL
-
-```xml
-<column>
-    <settings>
-        <dataType></dataType> <!-- creates wrapped UI component, column config = merge(wrapped.config + column.config) -->
-    </settings>
-</column>
-```
-
-DataType:
-- text - default
-
-Listing toolbar:
-```xml
-<listingToolbar>
-    <bookmark />
-    <columnsControls />
-    <filterSearch />
-    <filters />
-    <massaction>
-        <action name="delete">
-            <settings>
-                <label/>
-                <type/> - delete/edit/...
-                <url path=""/>
-                <confirm>
-                    <message/>
-                    <title/>
-                </confirm>
-                <callback>
-                    <target />
-                    <provider />
-                </callback>
-            </settings>
-        </action>
-    </massaction>
-    <paging />
-</listingToolbar>
-```
-
-
-Column types:
-- selection
-    ```xml
-    <selectionsColumn name="ids">
-        <settings>
-            <indexField>block_id</indexField>
-        </settings>
-    </selectionsColumn>
-    ```
-- select
-    ```xml
-    <column name="is_active" component="Magento_Ui/js/grid/columns/select">
-        <settings>
-            <options class="Magento\Cms\Model\Block\Source\IsActive"/>
-            <filter>select</filter>
-            <editor>
-                <editorType>select</editorType>
-            </editor>
-            <dataType>select</dataType>
-            <label translate="true">Status</label>
-        </settings>
-    </column>
-    ```
-- ...
-
-column/settings/filter:
-- textRange
-- text
-- select
-- dateRange
-- ...
-
-
-## UNSORTED
-
-Magento\Framework\Config\DataInterfaceFactory = \Magento\Ui\Config\Data::get('cert_form') -
-evil class that converts all the obscure UI component conventions into real understandable data array.
-E.g. `<settings>`, `<formElement>` and the like.
-
-Magento_Ui/view/base/ui_component/etc/definition.map.xml
-Magento_Ui/view/base/ui_component/etc/definition.xml
-
-- config data.initData
-- new config reader \Magento\Ui\Config\Reader('cert_form.xml')
-- config reader.read:
-  * find all UI files with this name
-  * reader.readFiles
-    + convert file contents to DOM \Magento\Ui\Config\Reader\Dom(file content) - new \DOMDocument.loadXML
-    + convert DOM to array - \Magento\Ui\Config\Converter::convert(DOMDocument)
-    + `config converter.toArray` -- all conventions start here
-      - merges default data by node name from `definition.xml`
-
-\Magento\Ui\Component\Filters: text, textRange, select, dateRange
-
-page layout - `urn:magento:framework:View/Layout/etc/page_configuration.xsd`
diff --git a/6. Developing with Adminhtml/4. Utilize ACL to set menu items and permissions.md b/6. Developing with Adminhtml/4. Utilize ACL to set menu items and permissions.md
deleted file mode 100644
index a95321a..0000000
--- a/6. Developing with Adminhtml/4. Utilize ACL to set menu items and permissions.md	
+++ /dev/null
@@ -1,267 +0,0 @@
-# Utilize ACL to set menu items and permissions
-
-## Describe how to set up a menu item and permissions.
-
-menu.xml - `urn:magento:module:Magento_Backend:/etc/menu.xsd` - flat structure
-```xml
-<menu>
-    <add id="Module_Alias::item_name" title="Title" translate="title" module="Module_Alias" sortOrder="30"
-      parent="Magento_Backend::system_design" action="adminhtml/system_design" resource="Magento_Backend::schedule"
-      dependsOnConfig="" dependsOnModule="" sortOrder="" target="" toolTip=""
-    />
-    <update id="Module_Alias::item_name" [all normal params] />
-    <remove id="Module_Alias::item_name" />
-</menu>
-```
-
-*How would you add a new tab in the Admin menu?*
-- don't specify parent and action
-
-*How would you add a new menu item in a given tab?*
-- just set one of top level parents, e.g. 'Magento_Backend::system'
-
-*How do menu items relate to ACL permissions?*
-
-## Describe how to check for permissions in the permissions management tree structures. 
-*How would you add a new user with a given set of permissions?*
-
-- System > Permissions > User Roles has all the differnet roles and associated permissions.  Each role can be scoped to Website level and granular permissions based on resource options. 
-- System > Permissions > All Users to view and create new users and associate to a role.  There are two tabs 1 is user info the other is User Role where you define the Role for this user.  You can only select 1 role per user.
-    
-*How can you do that programmatically?*
-- You can leverage [\Magento\Authorization\Model\Acl\AclRetriever](https://github.com/magento/magento2/blob/2.2-develop/app/code/Magento/Authorization/Model/Acl/AclRetriever.php).  That as a few methods that will help
-
-```php
-    /**
-     * Get a list of available resources using user details
-     *
-     * @param string $userType
-     * @param int $userId
-     * @return string[]
-     * @throws AuthorizationException
-     * @throws LocalizedException
-     */
-    public function getAllowedResourcesByUser($userType, $userId)
-    {
-        if ($userType == UserContextInterface::USER_TYPE_GUEST) {
-            return [self::PERMISSION_ANONYMOUS];
-        } elseif ($userType == UserContextInterface::USER_TYPE_CUSTOMER) {
-            return [self::PERMISSION_SELF];
-        }
-        try {
-            $role = $this->_getUserRole($userType, $userId);
-            if (!$role) {
-                throw new AuthorizationException(
-                    __('We can\'t find the role for the user you wanted.')
-                );
-            }
-            $allowedResources = $this->getAllowedResourcesByRole($role->getId());
-        } catch (AuthorizationException $e) {
-            throw $e;
-        } catch (\Exception $e) {
-            $this->logger->critical($e);
-            throw new LocalizedException(
-                __(
-                    'Something went wrong while compiling a list of allowed resources. '
-                    . 'You can find out more in the exceptions log.'
-                )
-            );
-        }
-        return $allowedResources;
-    }
-
-    /**
-     * Get a list of available resource using user role id
-     *
-     * @param string $roleId
-     * @return string[]
-     */
-    public function getAllowedResourcesByRole($roleId)
-    {
-        $allowedResources = [];
-        $rulesCollection = $this->rulesCollectionFactory->create();
-        $rulesCollection->getByRoles($roleId)->load();
-        $acl = $this->aclBuilder->getAcl();
-        /** @var \Magento\Authorization\Model\Rules $ruleItem */
-        foreach ($rulesCollection->getItems() as $ruleItem) {
-            $resourceId = $ruleItem->getResourceId();
-            if ($acl->has($resourceId) && $acl->isAllowed($roleId, $resourceId)) {
-                $allowedResources[] = $resourceId;
-            }
-        }
-        return $allowedResources;
-    } 
-```
-
-However the actual code to set privilage permission may look like this in the core code
-vendor/magento/magento2-base/setup/src/Magento/Setup/Fixtures/AdminUsersFixture.php
-
-In particular this section:
-
-```php
-            $adminUser = $this->userFactory->create();
-            $adminUser->setRoleId($role->getId())
-                ->setEmail('admin' . $i . '@example.com')
-                ->setFirstName('Firstname')
-                ->setLastName('Lastname')
-                ->setUserName('admin' . $i)
-                ->setPassword('123123q')
-                ->setIsActive(1);
-            $adminUser->save();
-```            
-
-```php
-<?php
-/**
- * Copyright © Magento, Inc. All rights reserved.
- * See COPYING.txt for license details.
- */
-
-namespace Magento\Setup\Fixtures;
-
-use Magento\Authorization\Model\Acl\Role\Group;
-use Magento\Authorization\Model\RoleFactory;
-use Magento\Authorization\Model\RulesFactory;
-use Magento\Authorization\Model\UserContextInterface;
-use Magento\Framework\Acl\RootResource;
-use Magento\User\Model\ResourceModel\User\CollectionFactory as UserCollectionFactory;
-use Magento\User\Model\UserFactory;
-
-/**
- * Generate admin users
- *
- * Support the following format:
- * <!-- Number of admin users -->
- * <admin_users>{int}</admin_users>
- */
-class AdminUsersFixture extends Fixture
-{
-    /**
-     * @var int
-     */
-    protected $priority = 5;
-
-    /**
-     * @var UserFactory
-     */
-    private $userFactory;
-
-    /**
-     * @var RoleFactory
-     */
-    private $roleFactory;
-
-    /**
-     * @var UserCollectionFactory
-     */
-    private $userCollectionFactory;
-
-    /**
-     * @var RulesFactory
-     */
-    private $rulesFactory;
-
-    /**
-     * @var RootResource
-     */
-    private $rootResource;
-
-    /**
-     * @param FixtureModel $fixtureModel
-     * @param UserFactory $userFactory
-     * @param UserCollectionFactory $userCollectionFactory
-     * @param RoleFactory $roleFactory
-     * @param RulesFactory $rulesFactory
-     * @param RootResource $rootResource
-     */
-    public function __construct(
-        FixtureModel $fixtureModel,
-        UserFactory $userFactory,
-        UserCollectionFactory $userCollectionFactory,
-        RoleFactory $roleFactory,
-        RulesFactory $rulesFactory,
-        RootResource $rootResource
-    ) {
-        parent::__construct($fixtureModel);
-        $this->userFactory = $userFactory;
-        $this->roleFactory = $roleFactory;
-        $this->userCollectionFactory = $userCollectionFactory;
-        $this->rulesFactory = $rulesFactory;
-        $this->rootResource = $rootResource;
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    public function execute()
-    {
-        $adminUsersNumber = $this->fixtureModel->getValue('admin_users', 0);
-        $adminUsersStartIndex = $this->userCollectionFactory->create()->getSize();
-
-        if ($adminUsersStartIndex >= $adminUsersNumber) {
-            return;
-        }
-
-        $role = $this->createAdministratorRole();
-
-        for ($i = $adminUsersStartIndex; $i <= $adminUsersNumber; $i++) {
-            $adminUser = $this->userFactory->create();
-            $adminUser->setRoleId($role->getId())
-                ->setEmail('admin' . $i . '@example.com')
-                ->setFirstName('Firstname')
-                ->setLastName('Lastname')
-                ->setUserName('admin' . $i)
-                ->setPassword('123123q')
-                ->setIsActive(1);
-            $adminUser->save();
-        }
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    public function getActionTitle()
-    {
-        return 'Generating admin users';
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    public function introduceParamLabels()
-    {
-        return [
-            'admin_users' => 'Admin Users'
-        ];
-    }
-
-    /**
-     * Create administrator role with all privileges.
-     *
-     * @return \Magento\Authorization\Model\Role
-     */
-    private function createAdministratorRole()
-    {
-        $role = $this->roleFactory->create();
-        $role->setParentId(0)
-            ->setTreeLevel(1)
-            ->setSortOrder(1)
-            ->setRoleType(Group::ROLE_TYPE)
-            ->setUserId(0)
-            ->setUserType(UserContextInterface::USER_TYPE_ADMIN)
-            ->setRoleName('Example Administrator');
-        $role->save();
-
-        /** @var \Magento\Authorization\Model\Rules $rule */
-        $rule = $this->rulesFactory->create();
-        $rule->setRoleId($role->getId())
-            ->setResourceId($this->rootResource->getId())
-            ->setPrivilegies(null)
-            ->setPermission('allow');
-        $rule->save();
-
-        return $role;
-    }
-}
-
-```
diff --git a/6.Magento-Developing-With-Adminhtml.md b/6.Magento-Developing-With-Adminhtml.md
new file mode 100755
index 0000000..fdb7101
--- /dev/null
+++ b/6.Magento-Developing-With-Adminhtml.md
@@ -0,0 +1,1225 @@
+6 - Developing with Adminhtml
+=============================
+
+6.1 Describe common structure/architecture
+------------------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**Describe the difference between Adminhtml and Frontend. What additional tools and requirements exist in the admin?**
+
+*   ACL permissions - _isAllowed, change static const ADMIN_RESOURCE
+*   Base controllers are different `Magento\Backend\App\Action` vs `Magento\Backend\App\AbstractAction` which accepts 4 parameters + pathPrefix (more on this below).
+*   Custom URL model which uses a secret key: key
+*   The layout acl block attribute
+*   File tree path structures are different:
+    *   `app/design/adminhtml` vs `app/design/frontend`
+    *   `<module_dir>/view/adminhtml` vs `<module_dir>/view/frontend`
+*   `UIComponents` are used in Adminhtml whereas they are not in Frontend.
+*   The `adminhtml` area code of `Magento\Framework\App\Area` includes and allows code needed for store management using `Magento\Framework\App\State` whereas frontend  contains template and layout files that define the appearance of your storefront only.
+
+![Magento Exam Information](./images/icon-info.png)Adminhtml & Frontend do share design paths in `<module_dir>/view/base` & `app/design/base` if common functionality exists between them.
+
+![Magento Exam Question](./images/icon-question.png)**What does router `id="admin"`, router `id="standard"` mean in routes.xml?**
+
+> The Standard Router (A.K.A the base router) sets module `frontName`, Controller Action names, Controller Module & Route Name if found. It processes all standard Magento URLs.
+>
+> The `frontName` attribute value becomes the part of our URL structure. Simply put, the URL formula for hitting the C.R.U.D action is formatted like:
+
+```
+<store-url>/<store-code>/<front-name>/<controller-name>/<action-name>
+```
+
+> The `id` attribute is the naming convention for Layout Handle XML and is formatted:
+
+```
+{route-id}_{controller-name}_{action-name}.xml
+```
+
+![Magento Exam Information](./images/icon-info.png)When configuring a custom routes.xml, it's easier to keep the id and frontName the same value.
+
+![Magento Exam Information](./images/icon-info.png)More information on Routers in [Section 2.3](#h.1jz2h7ynseok).
+
+![Magento Exam Question](./images/icon-question.png)**Some URLs in the backend start with "admin/admin/.." - 2 times admin, some only 1 - "admin/...". How?**
+
+![Magento Section Chevron](./images/icon-chevron.png)Config In Settings
+
+> The admin appears twice in the url when you have the flag:
+>
+>       Use Store Codes in the URL set = Yes.
+>
+> Since the admin section is actually a store view from Magento's point of view, its code (admin) is shown in the url.
+>
+>
+> The second time it appears it's because admin is the route key for the adminhtml controllers. For example, if you set a custom admin url key in the configuration:
+>
+> **System > Configuration > Admin > Admin Base URL > Custom Admin Path**
+>
+> The url will look like https:///example.com/admin/backend/controller/action/
+>
+> The First link hides behind `Magento_Backend`'s original `frontName` route `"adminhtml"="admin"`. The Second link has it's own `frontName="theme"` and is more beautiful.
+
+![Magento Section Chevron](./images/icon-chevron.png)Admin Workflow
+
+1.  bootstrap.run(application)
+2.  application.launch
+3.  front controller.dispatch
+4.  admin routerList: admin | default
+5.  `Magento\Backend\App\Router` (admin router) - Same as frontend `Magento\Framework\App\Router\Base` (standard router) except for:
+    *  It parses 4 sections:
+        1.  'areaFrontName' = area such as "admin" which uses "adminhtml" area code.
+        2.  'moduleFrontName' = The modules frontName e.g. "theme".
+        3.  'actionPath' The modules action Controller path e.g. "design_config".
+        4.  'actionName' The modules action method path e.g. "index" + additional query parameters such as /key/4bd2...13/
+    *  pathPrefix = 'adminhtml' -- all controller classes are searched in Module\Controller\Adminhtml\...
+6.  Module_Backend registers router i.e. getUrl("adminhtml/controller/action")
+
+6.2 Define form and grid widgets
+--------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**Define form structure, form templates, grids, grid containers, and elements. What steps are needed to display a grid or form?**
+
+![Magento Section Chevron](./images/icon-chevron.png)Step 1 - Define An ACL Resource
+
+See [Section 6.4](#h.8mv9vd67dqk5) on how to do this.
+
+![Magento Section Chevron](./images/icon-chevron.png)Step 2 - Define A Menu Item
+
+See [Section 6.4](#h.8mv9vd67dqk5) on how to do this.
+
+![Magento Section Chevron](./images/icon-chevron.png)Step 3 - Define A Route
+
+Define a new routes.xml in your custom module. The contents of this XML file tells Magento to route requests that use the frontName "exampleadminnewpage" to this module. The file is found in:
+
+`<module_dir>/etc/adminhtml/routes.xml`
+
+Example `MyVendor/MyModule/Controller/MyExampleAdminPage/Index.php`:
+```xml
+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:App/etc/routes.xsd">
+        <router id="admin">
+                   <route id="exampleadminnewpage" frontName="exampleadminnewpage">
+                       <module name="MyVendor_MyModule"/>
+                   </route>
+        </router>
+</config>
+```
+![Magento Section Chevron](./images/icon-chevron.png)Step 4 - Create A Controller & Layout Handle
+
+> A layout handle is a uniquely identified set of layout instructions that serves as a name of a layout file.
+> The id attribute of the <route> node defined above will be the naming convention for this Layout Handle XML and is formatted and found in:
+
+```
+<module_dir>/view/adminhtml/{route-id}_{controller-name}_{action-name}.xml
+```
+> In this example it would be `exampleadminnewpage_myexampleadminnewpage_index.xml`
+
+![Magento Exam Information](./images/icon-info.png)More on [Layout Handles here.](https://devdocs.magento.com/guides/v2.4/frontend-dev-guide/layouts/layout-overview.html%23layout-over-terms&sa=D&ust=1609223265050000&usg=AOvVaw3_snUU799Zu0QeeZjg_QQp)
+
+Example Layout Handle with `uiComponent` node:
+
+```xml
+<?xml version="1.0"?>
+<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
+        <body>
+                   <referenceContainer name="content">
+                               <uiComponent name="example_admin_new_page" />
+                   </referenceContainer>
+        </body>
+</page>
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)Create A UI Component
+
+> Magento UI components are used to represent distinct UI elements, such as tables, buttons, dialogs, and others. They are designed for simple and flexible user interface (UI) rendering.
+> UI component is a combination of:
+
+*   XML declaration that specifies the component's configuration settings and inner structure.
+*   JavaScript class inherited from one of the Magento JavaScript framework UI components base classes (such as `UIElement`, `UIClass` or `UICollection`).
+*   Related template(s)
+
+> UI Component is configured through a dedicated XML file:
+
+```
+<module_dir>/view/<adminhtml/base>/ui_component/{ui_component_name.xml}
+```
+
+In this example:
+
+```
+MyVendor/MyModule/view/adminhtml/ui_component/example_admin_new_page.xml
+```
+> For Adminhtml, UI Components take the form of either a [UI Form Component](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-form.html&sa=D&ust=1609223265053000&usg=AOvVaw3wKYwjnzCE7AQFh-Muy2TU) or [UI Listing (Grid) Component](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-listing-grid.html&sa=D&ust=1609223265054000&usg=AOvVaw2jmBXaNRZ1CBqWh9CRKQxi).
+
+*   How to create a UI Listing (Grid)Component: [Please refer to the section below](#h.sa9xmdshqqtr)
+*   How to make a UI Form Component: [Please refer to the section below](#h.zewrzi9tl4q3)
+
+![Magento Section Chevron](./images/icon-chevron.png)Step 6 - Define a DataSource Provider Component
+
+> Magento provides the [DataSource](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/concepts/ui_comp_data_source.html&sa=D&ust=1609223265055000&usg=AOvVaw2xYsbx67HiCgYdW7Zg2WDf) object, which is designed to interact with data in your UI component. Many of the core UI components use this DataSource component. Many UI components require that this object is included. However, there are specific requirements in order for it to work correctly.
+>
+> For more information, please refer to the [DataSource Provider Component section](#h.kg229a1fn1nm) below.
+
+![Magento Section Chevron](./images/icon-chevron.png)Step 7 - Define & Create Actions
+
+```xml
+<type name="Magento\Framework\View\Element\UiComponent\DataProvider\CollectionFactory">
+        <arguments>
+                   <argument name="collections" xsi:type="array">
+                                <item name="example_admin_new_page_grid_data_source" xsi:type="string">MyVendor\MyModule\Model\ResourceModel\CustomAdminPage\Grid\Collection</item>
+                   </argument>
+        <arguments>
+</type>
+```
+
+Example `MyVendor/MyModule/view/adminhtml/ui_component/example_admin_new_page.xml`:
+
+![Magento Exam Question](./images/icon-question.png)**Describe the grid and form workflow.**
+
+![Magento Section Chevron](./images/icon-chevron.png)Server Side
+
+1.  Layout handle loads UI component
+2.  XML files of UI component are searched in each enabled module (`<module_dir>/view/<area>/ui_component/<ui_component_name>.xml`)
+3.  All found files of UI components are merged in a single configuration object
+4.  Configuration and definition.xml are merged. Objects from definition.xml have lower priority than single configuration object, received in the previous step
+5.  The received configuration is transformed into JSON and embedded into the page with Magento\Ui\TemplateEngine\Xhtml\Result class
+
+As a result, we get the following outputted JSON code:
+
+```html
+<script type="text/x-magento-init">
+{
+    "*": {
+        "Magento_Ui/js/core/app": {
+            "types":{ ... },
+
+            "components":{ ... }
+        }
+    }
+}
+</script>
+```
+![Magento Exam Information](./images/icon-info.png)To help remember this, think about how Magento [Adminhtml standard router](#h.eyiqynfna8fc) requests work then add the extra UI Component / Configuration / definition.xml
+
+![Magento Section Chevron](./images/icon-chevron.png)Client Side
+
+1.  RequireJS loads `Magento_Ui/js/core/app` and passes configuration as a parameter.
+2.  `Magento_Ui/js/core/app` calls `Magento_Ui/js/core/renderer/layout` and passes it the configuration.
+3.  layout.js creates instances of UI components and applies the configuration to it
+4.  HTML template rendering with knockout.js and binding of the component to the template is performed
+
+[Data Source](#h.kg229a1fn1nm)
+
+The data for grid and form is loaded with the help of [DataProvider](#h.kg229a1fn1nm). The difference lies in the moment of information upload.
+
+[Form Component](#h.zewrzi9tl4q3)
+> For the form component, the data of an entity are passed inside the current page's html code in the `<script type = "text / x-magento-init"> ... </script>` tag.
+>
+> [Grid Component](#h.sa9xmdshqqtr)For the grid component, the data is loaded through an additional ajax request for the controller action `mui/index/render`, processed by the `Magento\Ui\Controller\Adminhtml\Index\Render` for `adminhtml` area and `Magento\Ui\Controller\Index\Render` for frontend area .
+
+![Magento Exam Question](./images/icon-question.png)**How is data provided to the grid or form?**
+
+### ![Magento Section Chevron](./images/icon-chevron.png)DataSource Provider Component
+
+> Magento provides the [DataSource](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/concepts/ui_comp_data_source.html&sa=D&ust=1609223265063000&usg=AOvVaw3alkjPHTsH5uBc0r_NfY_q) object, which is designed to interact with data in your UI component. Many of the core UI components use this DataSource component. Many UI components require that this object is included. However, there are specific requirements in order for it to work correctly.
+>
+> Using `Magento_Ui/view/base/ui_component/etc/definition.map.xml` we can deduce full <dataSource> definition and what parameter will end up where:
+
+```xml
+<dataSource class="Magento\Ui\Component\DataSource">
+   <aclResource/>
+   <settings>
+       <submitUrl />
+       <validateUrl />
+       <updateUrl/>
+       <filterUrlParams/>
+       <storageConfig/>
+       <statefull/>
+       <imports/>
+       <exports/>
+       <links/>
+       <listens/>
+       <ns/>
+       <componentType/>
+       <dataScope/>
+       <deps/>
+       <layout>
+           <type/>
+           <navContainerName/>
+       </layout>
+   </settings>
+   <dataProvider name="some_name" class="SomeDataProviderClass">
+       <settings>
+           <primaryFieldName>entity_id</primaryFieldName>
+           <requestFieldName>id</requestFieldName>
+       </settings>
+   </dataProvider>
+</dataSource>
+```
+
+`**<dataSource>**`:
+
+```xml
+<argument name="data" xsi:type="array">
+    <item name="js_config" xsi:type="array">
+        <item name="provider" xsi:type="string">[ComponentName].[ComponentName]_data_source</item>
+        <item name="deps" xsi:type="string">[ComponentName].index_listing_data_source</item>
+    </item>
+</argument>
+<dataSource name="index_listing_data_source" component="Magento_Ui/js/grid/provider">
+        <settings>
+           <updateUrl path="mui/index/render"/>
+        </settings>
+        <aclResource>Vendor_MyModule::view</aclResource>
+        <dataProvider class="MyVendor\MyModule\Ui\Component\CustomAdminPage\Listing\DataProvider" name="index_listing_data_source">
+           <settings>
+               <requestFieldName>id</requestFieldName>
+               <primaryFieldName>main_table.id</primaryFieldName>
+           </settings>
+        </dataProvider>
+</dataSource>
+```
+
+![Magento Exam Information](./images/icon-info.png)In our example [ComponentName] = `example_admin_new_page` which matches the `ui_component` XML file name.
+
+> The main node of interest is `<dataProvider class="">`. This references a PHP class that MUST implement `Magento\Framework\View\Element\UiComponent\DataProvider\DataProviderInterface` to meet that requirement, it can extend the following classes:
+
+*   `Magento\Ui\DataProvider\AbstractDataProvider`
+*   `Magento\Framework\View\Element\UiComponent\DataProvider\DataProvider`
+
+> The node `<item name="js_config">` is a good way to keep configuration data out of the JavaScript. It accepts:
+
+*   `<item name="provider" xsi:type="string">` = will output in the JSON that will contain the UI component's configuration.
+*   `<item name="deps" xsi:type="string">` = the name="" of your `<dataSource>` in which will be the provider.
+*   `<item name="component" xsi:type="string">` = the `jsComponent` of your UI Component, for a form use `Magento_Ui/js/form/provider`. For a grid use `Magento_Ui/js/grid/provider`. These can be extended if it does not do exactly what you need.
+
+> Other nodes of interest / importance include:
+
+[Javascript Component Linking](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/concepts/ui_comp_linking_concept.html&sa=D&ust=1609223265069000&usg=AOvVaw0SFEbEvoRrG9pkBcjHPUyq)
+
+> Every Javascript component should extend the core [uiElement](#h.h647tzfdps5a) class in some way. When this class initializes it runs an `initLinks()` method. That method, in turn, passes a few class properties into a method that handles linking components together. This file (`lib/core/element/link.js`) binds the values of those parameters to actual components.
+>
+> The properties Magento will parse are:
+
+*   `imports`
+*   `exports`
+*   `links`
+
+
+
+[**`<exports/>`**](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/concepts/ui_comp_linking_concept.html%23exports-property&sa=D&ust=1609223265070000&usg=AOvVaw3MmS_8QmSLuPiyk8ipbrWi) [](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/concepts/ui_comp_linking_concept.html%23exports-property&sa=D&ust=1609223265071000&usg=AOvVaw0rVCuPuhkMyBKUTZ0bVJCN)
+
+> The `<exports>` property is used to copy a local value to some external entity. Exports's value is an object, composed of the following:
+
+```xml
+<argument name="data" xsi:type="array">
+    <item name="config" xsi:type="array">
+        <item name="exports" xsi:type="array">
+            <item name="visible" xsi:type="string">sample_config.sample_provider:visibility</item>
+        </item>
+    </item>
+</argument>
+```
+
+> Here visible is the key, `${ $.provider }:visibility` is the value. The value of the local visible property is assigned to the visibility property of the provider component. The latter is changed automatically if the value of visible changes if the local visible property is an ko io-es5 observable (which it isn't given in the code example above).
+>
+> Within the jsComponent's defaults property:
+
+```json
+{
+    "defaults": {
+        "exports": {
+            "visible": "${ $.provider }:visibility"
+        }
+    }
+}
+```
+
+[**`<imports />`**](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/concepts/ui_comp_linking_concept.html%23imports-property&sa=D&ust=1609223265074000&usg=AOvVaw1PwT5VH-B53vSSOuakgaaW) [](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/concepts/ui_comp_linking_concept.html%23imports-property&sa=D&ust=1609223265075000&usg=AOvVaw1FmY-MwOGmfanHwMqKffRp)
+
+> The `<imports>` property is used for tracking changes of an external entity property. imports's value is an object, composed of the following:
+
+```xml
+<argument name="data" xsi:type="array">
+    <item name="config" xsi:type="array">
+        <item name="imports" xsi:type="array">
+            <item name="visible" xsi:type="string">sample_config.sample_provider:visibility</item>
+        </item>
+    </item>
+</argument>
+```
+
+> Within the `jsComponent`'s defaults property:
+```json
+{
+    "defaults": {
+        "imports": {
+            "visible": "${ $.provider }:visibility"
+        }
+    }
+}
+```
+
+[**`<links />`**](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/concepts/ui_comp_linking_concept.html%23links-property&sa=D&ust=1609223265162000&usg=AOvVaw1Zqt-qaZoI8fYWmbnqSdGL)
+
+> The links property is used for cross tracking properties changes (import and export combined): both linked properties are tracked and changing of one results in changing the other. links's value is an object, composed of the following:
+
+```xml
+<argument name="data" xsi:type="array">
+    <item name="config" xsi:type="array">
+        <item name="links" xsi:type="array">
+            <item name="visible" xsi:type="string">sample_config.sample_provider:visibility</item>
+        </item>
+    </item>
+</argument>
+```
+
+> The links property of a `jsComponent` is the same as duplicating a value in both imports and exports. Each of those properties expect an object that contains key/value pairs to bind the expression to. In the example above, it would appear in the defaults property like this:
+
+```json
+{
+    "defaults": {
+        "links": {
+            "visibility": "${ $.provider }:data.visibility"
+        }
+    }
+}
+```
+
+[**`<listens />`**](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/concepts/ui_comp_linking_concept.html%23listens-property&sa=D&ust=1609223265165000&usg=AOvVaw38P_R1lCCCZz9056X56hAv)
+
+> The `<listens />` property is used to track the changes of a component's property. listens's value is an object, composed of the following:
+
+```xml
+<argument name="data" xsi:type="array">
+    <item name="config" xsi:type="array">
+        <item name="listens" xsi:type="array">
+            <item name="sample_config.sample_provider:visibility" xsi:type="string">visibilityChanged</item>
+        </item>
+    </item>
+</argument>
+```
+
+> In this example, the local `visibilityChanged` property is a method that will be called when the visibility property of the provider component changes. It receives the new value as an argument but, if the local property is not a function, it will be set to the new value (although the external property has to be a KO observable in order for listens to have any effect).
+
+[**Template Literals**](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/concepts/ui_comp_data_source.html%23javascript-template-literals&sa=D&ust=1609223265168000&usg=AOvVaw1wOfWejMB5DNqB78Zn-qOf)
+
+> Throughout Magento's core Javascript components there are strings like this: `'${ $.provider }:data.totalRecords'`. These are [ES2015 template literals](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Template_literals&sa=D&ust=1609223265168000&usg=AOvVaw2lF6Qy8tT5c88sbKBv5Glr). The `${ }` surrounds an expression that will be parsed as Javascript. `$.provider` is the expression, in this example.
+>
+> When the `uiElement` class initializes, it will process the link that was declared in imports. Remember that one of the first things Magento does is process string literals, though, so it is actually working with something that looks more like the following:
+
+```json
+{
+    "defaults": {
+        "exports": {
+            "items": "checkout.sidebar.summary.cart_items:items"
+        }
+    }
+}
+```
+
+![Magento Exam Question](./images/icon-question.png)**How can this process be customized or extended?**
+
+> You can change the form data the following ways:
+
+1.  Create a custom [`DataProvider`](#h.kg229a1fn1nm) and specify it in the xml file of the UI component.
+2.  Create a plugin for `DataProvider::getData()` method
+3.  Create Modifier class and set it in `di.xml`, if this DataProvider support Modifiers (for example, like `Magento\Catalog\Ui\DataProvider\Product\Form\ProductDataProvider`)
+
+![Magento Exam Question](./images/icon-question.png)**Describe how to create a simple form and grid for a custom entity. Given a specific entity with different types of fields (text, dropdown, image, file, date, and so on) how would you create a grid and a form?**
+
+### ![Magento Section Chevron](./images/icon-chevron.png)UI Listing (Grid) Component
+
+> Listing is a user interface component that implements grids, lists and tiles with filtering, pagination, sorting and other features. Much like the `sales_order_grid`
+>
+> Listing (Grid) is a [Basic Component](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/bk-ui_comps.html%23general-structure&sa=D&ust=1609223265175000&usg=AOvVaw0hhtFjgtvRoapdhB9wIGHs).
+
+UI Grid Listing config tree:
+
+| Root Node | Description | Child Nodes |
+| --- | --- | --- |
+| `<argument name="data">` | Related to the `<dataSource>` | `<item name="">`, `js_config`, `provider`, `deps` , `spinner` |
+| [`<button>`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-button.html&sa=D&ust=1609223265178000&usg=AOvVaw2HIVdlAmH2V4QINvtnrAcY) | The Button component allows user to perform a list of predefined actions by clicking on the corresponding button | `<argument name="data">`, `<item name="">`, `config`, `buttonClasses`, `actions`, `<settings>`, `<displayAsLink>`, `<title>` |
+| [`<columns>`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-columns.html&sa=D&ust=1609223265180000&usg=AOvVaw1ffebj8wB3dZpPcvdfNopD) | The Columns component is a collection of columns. It renders the `<table>` element. | [`<actionsColumn name="">`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-actionscolumn.html&sa=D&ust=1609223265181000&usg=AOvVaw02665LNSh1uzuqDqt5dxPs),  [`<selectionsColumn name="">`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-listing-grid.html&sa=D&ust=1609223265181000&usg=AOvVaw28o5s1u_yivq4_egWZeeGy), [`<column name="">`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-column.html&sa=D&ust=1609223265182000&usg=AOvVaw0kWnrSFlSvQshvbS_rzf9d) - [`DateColumn`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-datecolumn.html&sa=D&ust=1609223265182000&usg=AOvVaw0EY30QVWjvZqTj1Px1ZibK), [`ExpandableColumn`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-expandable-column.html&sa=D&ust=1609223265183000&usg=AOvVaw1M-iLMi8kC9iztUv5oN8hT), [`ImagePreviewColumn`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-image-preview.html&sa=D&ust=1609223265183000&usg=AOvVaw29LjZERV29Yg_udnCHE7_u), [`LinkColumn`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-linkcolumn.html&sa=D&ust=1609223265184000&usg=AOvVaw3UPi8KNeW4_wxiuk5hVDh1), [`MultiselectColumn`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-multiselectcolumn.html&sa=D&ust=1609223265185000&usg=AOvVaw3bQVM8bDeYocJ3Q_uIefar), [`OnOffColumn`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-onoffcolumn.html&sa=D&ust=1609223265185000&usg=AOvVaw1QUF4tKZ8Cv9mSWnDsj8Df), [`RangeColumn`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-range.html&sa=D&ust=1609223265186000&usg=AOvVaw31RAOlbqMyzYKywB4-ygmb), [`ThumbnailColumn`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-thumbnailcolumn.html&sa=D&ust=1609223265186000&usg=AOvVaw1g8qyMT0m_1_KTDXMItWio). `<settings>` - [`DragAndDrop`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-draganddrop.html&sa=D&ust=1609223265187000&usg=AOvVaw2Ks4C5ZvHoEco-fULGKnPC)
+| `<container>` | | [`<exportButton name="">`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-exportbutton.html&sa=D&ust=1609223265188000&usg=AOvVaw3ve72X2B7eiSfWB8tYYoFM) |
+| [`<dataSource component="" name="">`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-listing-grid.html%23configure-datasource&sa=D&ust=1609223265189000&usg=AOvVaw2Lj40IujkzENQ0QjdmMKFV) | Another UI component that provides data in specific format which is shared among all UI components. `component="Magento_Ui/js/form/provider"` The listing component requires the data source to be properly configured and associated with it.| `<aclResource>`, `<dataProvider class="" name="">`.  `<settings>` - `requestFieldName`, `primaryFieldName`. `<settings>` - `<updateUrl path="mui/index/render" />`, `<submitUrl path="">`, `<validateUrl path="">` |
+| [`<listingToolbar>`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-toolbar.html&sa=D&ust=1609223265191000&usg=AOvVaw0B-bvEJftL2GFYKKQ0s1T4) | | [`<bookmark name="">`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-bookmarks.html&sa=D&ust=1609223265192000&usg=AOvVaw3DIIJXn3ERhUpA9amWAlmb). [`<columnsControls>`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-columnscontrols.html&sa=D&ust=1609223265192000&usg=AOvVaw2BzZc1tbT5_mejs1oYlHYD). [`<filters name="">`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-filters.html&sa=D&ust=1609223265193000&usg=AOvVaw0dRuPU3JiVO0J8-4hodugI)- [`FilterChips`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-filterschips.html&sa=D&ust=1609223265193000&usg=AOvVaw0nioNbiZjb1gKUb-BneYBN). [`<massaction name="">`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-massactions.html&sa=D&ust=1609223265193000&usg=AOvVaw0FsMbUhFHLiG7ko4xs_VPm)- [`TreeMassActions`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-treemassactions.html&sa=D&ust=1609223265194000&usg=AOvVaw2FgFI8D9SFuir_LPG7X16k). [`<paging name="">`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-paging.html&sa=D&ust=1609223265195000&usg=AOvVaw21L-5MCQdoYLp0PrFCRz8c)-  [`SizesComponent`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-sizes.html&sa=D&ust=1609223265195000&usg=AOvVaw3Xzoz7vLKnsjl0Y6WixQG9). [<filterSearch name="fulltext"/>](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-search.html&sa=D&ust=1609223265195000&usg=AOvVaw0QMMZRV-Sm-oQd3r-ASeR7) |
+| [`<filterSelect name="uiSelect">`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-filters.html&sa=D&ust=1609223265196000&usg=AOvVaw2vq9IXzgW5UYB9wGwdmkM-) | The UI-select component is a single select/multiple select component that enables the selection of a collection of items. It extends all abstract configuration and can be configured in two modes: 1. Single - checkbox isn't displayed. 2. Multiple - checkboxes are displayed | |
+| `<settings>` | Additional configurations such as multiple buttons | |
+
+![Magento Exam Information](./images/icon-info.png)Nodes such as <settings> are part of a UI Components [Basic Configuration Elements](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/concepts/ui_comp_xmlconfig_structure.html%23basic-configuration-elements&sa=D&ust=1609223265198000&usg=AOvVaw3T0HieVxAXSX9areVgrr9T). You can find all available settings for each node in the XSD of that XML file.
+
+> UI Grid Listing Example `MyVendor/MyModule/view/adminhtml/ui_component/example_admin_new_page.xml`):
+
+```xml
+<?xml version="1.0" encoding="UTF-8"?>
+
+<listing xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Ui:etc/ui_configuration.xsd">
+    <argument name="data" xsi:type="array">
+        <item name="js_config" xsi:type="array">
+            <item name="provider" xsi:type="string">custom_admin_grid.custom_admin_grid</item>
+            <item name="deps" xsi:type="string">custom_admin_grid.custom_admin_grid_data_source</item>
+        </item>
+        <item name="spinner" xsi:type="string">convert_monitor_indexers_catalogindexers_columns</item>
+    </argument>
+    <settings>
+        <buttons>
+            <button name="add" class="MyVendor\MyModule\Block\Adminhtml\CustomAdminPage\Button\Add" />
+        </buttons>
+    </settings>
+    <dataSource name="custom_admin_grid_data_source" component="Magento_Ui/js/grid/provider">
+        <settings>
+            <updateUrl path="mui/index/render"/>
+        </settings>
+        <aclResource>Convert_MonitorIndexers::config</aclResource>
+        <dataProvider class="MyVendor\MyModule\Ui\Component\CustomAdminPage\DataProvider" name="custom_admin_grid_data_source">
+            <settings>
+                <requestFieldName>id</requestFieldName>
+                <primaryFieldName>main_table.id</primaryFieldName>
+            </settings>
+        </dataProvider>
+    </dataSource>
+    <listingToolbar name="listing_top">
+        <argument name="data" xsi:type="array">
+            <item name="config" xsi:type="array">
+                <item name="sticky" xsi:type="boolean">true</item>
+            </item>
+        </argument>
+        <bookmark name="bookmarks"/>
+        <columnsControls name="columns_controls"/>
+        <filters name="listing_filters"/>
+        <!-- todo Add some mass actions ?
+           <massaction name="listing_massaction">
+           </massaction>-->
+        <paging name="listing_paging"/>
+    </listingToolbar>
+    <columns name="convert_monitor_indexers_catalogindexers_columns">
+        <selectionsColumn name="id">
+            <argument name="data" xsi:type="array">
+                <item name="config" xsi:type="array">
+                    <item name="indexField" xsi:type="string">id</item>
+                    <item name="sortOrder" xsi:type="number">10</item>
+                </item>
+            </argument>
+        </selectionsColumn>
+        <column name="id">
+            <argument name="data" xsi:type="array">
+                <item name="config" xsi:type="array">
+                    <item name="filter" xsi:type="string">textRange</item>
+                    <item name="sorting" xsi:type="string">asc</item>
+                    <item name="label" xsi:type="string" translate="true">Entity ID</item>
+                    <item name="sortOrder" xsi:type="number">20</item>
+                </item>
+            </argument>
+        </column>
+        <actionsColumn name="actions" class="MyVendor\MyModule\Ui\Component\CustomAdminPage\Listing\Columns\Actions">
+            <argument name="data" xsi:type="array">
+                <item name="config" xsi:type="array">
+                    <item name="indexField" xsi:type="string">id</item>
+                    <item name="urlEntityParamName" xsi:type="string">id</item>
+                    <item name="sortOrder" xsi:type="number">20</item>
+                </item>
+            </argument>
+        </actionsColumn>
+    </columns>
+</listing>
+```
+### ![Magento Section Chevron](./images/icon-chevron.png)UI Form Component
+
+> The Form is a user interface component comprising a collection of fields that can be grouped in tabs and fieldsets. It enables CRUD operations.
+>
+> Form is a [Basic Component](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/bk-ui_comps.html%23general-structure&sa=D&ust=1609223265204000&usg=AOvVaw2yXqzXs1pa68_nGBJ8Zsox).
+
+UI Form config tree:
+
+| Root Node | Description | Child Nodes |
+| --- | --- | --- |
+| [`<dataSource>`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-listing-grid.html%23configure-datasource&sa=D&ust=1609223265206000&usg=AOvVaw3rtUKHEqG1esZzIRIsfbkX) | Another UI component that provides data in specific format which is shared among all UI components. `component="Magento_Ui/js/form/provider"`. The listing component requires the data source to be properly configured and associated with it | `<aclResource>`. `<dataProvider class="" name="">` - `<settings>`, `requestFieldName`, `primaryFieldName`. `<settings>` | `<updateUrl path="mui/index/render" />`, `<submitUrl path="">`, `<validateUrl path="">` |
+| [`<dynamicRows>`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-dynamicrows.html&sa=D&ust=1609223265208000&usg=AOvVaw1IcwGj8Pfx2oPdYMt0odXf) | The DynamicRows component is a dynamic collection of records. The user can edit the records, change their position, and navigate through the collection. | [`<actionDelete>`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-actiondelete.html&sa=D&ust=1609223265209000&usg=AOvVaw36zvk8JurMWGum0-2pDYFY) |
+| [`<fieldset>`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-fieldset.html&sa=D&ust=1609223265210000&usg=AOvVaw27X1by2FHaKIge9oZDffxj) | The Fieldset component implements a container for visually-grouped form elements, such as buttons and form fields. | [`<checkboxset>`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-checkboxset.html&sa=D&ust=1609223265211000&usg=AOvVaw0dygZiHW8UpcpeCr-Qu6cu) - `<argument name="data">`, `<item name="config">`. `additionalInfo`. [`<email>`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-email.html&sa=D&ust=1609223265213000&usg=AOvVaw1Z2T9DUJT0L4OKJQD0GbA1). `<field name="">` - `<argument name="data">` - `<item name="config">` - , `label`, `visible`, `dataType`, `formElement`. [`FileUploader`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-fileuploader.html&sa=D&ust=1609223265214000&usg=AOvVaw1GFjD8UtgyFPmhAnGKlBKl) component - `<formElements>`. [`<checkbox>`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-checkbox.html&sa=D&ust=1609223265214000&usg=AOvVaw1hQ5sYML23v8HCYz26whSE). [`Input`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-input.html&sa=D&ust=1609223265215000&usg=AOvVaw2Lyb4lHEwf8WpaT4irYGp6) component. [`Multiline`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-multiline.html&sa=D&ust=1609223265215000&usg=AOvVaw1uONLAYgNCZGyYxgEHUm_6) component. [`Multiselect`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-multiselect.html&sa=D&ust=1609223265215000&usg=AOvVaw3DT6Zl4Qn4skyoTJJCcXXW) component. [`Text`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-text.html&sa=D&ust=1609223265216000&usg=AOvVaw0erIwFc0uYF3YmpHwvtF-z) component. [`Textarea`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-textarea.html&sa=D&ust=1609223265216000&usg=AOvVaw1KOcz2HlCqxPBPHg-MCRcC) component [`WYSIWYG`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-wysiwyg.html&sa=D&ust=1609223265217000&usg=AOvVaw2z2nRGSZUvCNrjr85HoV75) compon nt. [`<fieldset>`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-fieldset.html&sa=D&ust=1609223265218000&usg=AOvVaw3z2xCQD8TB3JVI-Fz9dg9_) (can p rent itself). [`<file>`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-file.html&sa=D&ust=1609223265218000&usg=AOvVaw3om7m7_z28KfT_UF7BDi2s). [`<hidd n>`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-hidden.html&sa=D&ust=1609223265219000&usg=AOvVaw2Ne25XVISOw3SkiF8XDMFA). [`<radioset `](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-radioset.html&sa=D&ust=1609223265219000&usg=AOvVaw31LGPvUqumVJycQ8bYnRQK). [`<select>`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-select.html&sa=D&ust=1609223265220000&usg=AOvVaw11Y_HSdFLrBt-NOVt6xn4V). `<settings>` - `<options>`, `<option>`, `<item name="value">`, `<item name="label">`, `<caption>`, `<label>`. |
+| [`<htmlContent>`](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/components/ui-htmlcontent.html&sa=D&ust=1609223265221000&usg=AOvVaw1zHXq5F252nqEB7lsyXH_e) | The HtmlContent UI component provides the ability to process and render a layout structure or a Magento block directly inside a UI component configuration. Processing and rendering is executed on the server side.| [`<block>`](https://devdocs.magento.com/guides/v2.4/frontend-dev-guide/layouts/xml-instructions.html%23fedg_layout_xml-instruc_ex_block&sa=D&ust=1609223265222000&usg=AOvVaw0lHNlnmmym9laLeJMrNmyP) |
+
+![Magento Exam Information](./images/icon-info.png)Nodes such as <settings> are part of a UI Components [Basic Configuration Elements](https://devdocs.magento.com/guides/v2.4/ui_comp_guide/concepts/ui_comp_xmlconfig_structure.html%23basic-configuration-elements&sa=D&ust=1609223265223000&usg=AOvVaw3UFGegwqs4mIGNHKfkevGT). You can find all available settings for each node in the XSD of that XML file.
+
+UI Form Example:
+```xml
+<form xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Ui:etc/ui_configuration.xsd">
+    <argument name="data" xsi:type="array">
+        <item name="js_config" xsi:type="array">
+            <item name="provider" xsi:type="string">customer_form.customer_form_data_source</item>
+        </item>
+        <item name="label" xsi:type="string" translate="true">Customer Information</item>
+        <item name="reverseMetadataMerge" xsi:type="boolean">true</item>
+    </argument>
+    <dataSource name="customer_form_data_source">
+        <argument name="data" xsi:type="array">
+            <item name="js_config" xsi:type="array">
+                <item name="component" xsi:type="string">Magento_Ui/js/form/provider</item>
+            </item>
+        </argument>
+        <settings>
+            <validateUrl path="customer/index/validate" />
+            <submitUrl path="customer/index/save" />
+        </settings>
+        <dataProvider class="MyVendor\MyModule\Model\Customer\DataProvider" name="customer_form_data_source">
+            <settings>
+                <requestFieldName>id</requestFieldName>
+                <primaryFieldName>entity_id</primaryFieldName>
+            </settings>
+        </dataProvider>
+    </dataSource>
+    <fieldset name="customer">
+        <settings>
+            <label translate="true">Account Information</label>
+        </settings>
+        <field name="entity_id" formElement="input">
+            <argument name="data" xsi:type="array">
+                <item name="config" xsi:type="array">
+                    <item name="source" xsi:type="string">customer</item>
+                </item>
+            </argument>
+            <settings>
+                <dataType>text</dataType>
+                <visible>false</visible>
+            </settings>
+        </field>
+    </fieldset>
+    <settings>
+        <buttons>
+            <button name="save_and_continue" class="MyVendor\MyModule\Block\Adminhtml\Edit\SaveAndContinueButton" />
+            <button name="save" class="MyVendor\MyModule\Block\Adminhtml\Edit\SaveButton" />
+            <button name="reset" class="MyVendor\MyModule\Block\Adminhtml\Edit\ResetButton" />
+            <button name="order" class="MyVendor\MyModule\Block\Adminhtml\Edit\OrderButton" />
+            <button name="resetPassword" class="MyVendor\MyModule\Block\Adminhtml\Edit\ResetPasswordButton" />
+            <button name="unlock" class="MyVendor\MyModule\Block\Adminhtml\Edit\UnlockButton" />
+            <button name="invalidateToken" class="MyVendor\MyModule\Block\Adminhtml\Edit\InvalidateTokenButton" />
+            <button name="delete" class="MyVendor\MyModule\Block\Adminhtml\Edit\DeleteButton" />
+            <button name="back" class="MyVendor\MyModule\Block\Adminhtml\Edit\BackButton" />
+        </buttons>
+        <layout>
+            <navContainerName>left</navContainerName>
+            <type>tabs</type>
+        </layout>
+        <deps>
+            <dep>customer_form.customer_form_data_source</dep>
+        </deps>
+    </settings>
+</form>
+```
+
+6.3 Define system configuration XML and configuration scope
+-----------------------------------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**Define basic terms and elements of system configuration XML, including scopes.**
+
+> The `system.xml` file allows you to manage the Magento system configuration. Use this topic as a general reference for the `system.xml` file. The system.xml file is located under `etc/adminhtml/system.xml` in a given Magento 2 extension.
+>
+> Tabs // Sections // Groups // Fields
+>
+> In the `system.xml` file, it is possible to define four different types of entities: tabs, sections, groups, and fields. Each related but rest in different sections of Admin > Stores > Configuration. Like so: ![](./images/magento2-system-configuration.png)
+
+#### system.xml
+
+`etc/adminhtml/system.xml`:
+```xml
+<?xml version="1.0"?>
+
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Config:etc/system_file.xsd">
+    <system>
+        <tab id="my_vendor" translate="label" sortOrder="0">
+            <label>Example Vendor</label>
+        </tab>
+        <section id="convert" translate="label" type="text" sortOrder="0" showInDefault="1" showInWebsite="0" showInStore="0">
+            <label>General</label>
+            <tab>my_vendor</tab>
+            <resource>MyVendor_MyModule::config</resource>
+            <group id="general" showInDefault="1" showInStore="1" showInWebsite="1" sortOrder="10" translate="label">
+                <label>Settings</label>
+                <field id="debug" showInDefault="1" showInStore="1" showInWebsite="1" sortOrder="10" translate="label" type="select">
+                    <label>Debug</label>
+                    <comment>Enable debug mode for module</comment>
+                    <source_model>Magento\Config\Model\Config\Source\Enabledisable</source_model>
+                </field>
+            </group>
+        </section>
+    </system>
+</config>
+```
+### ![Magento Section Chevron](./images/icon-chevron.png)Tabs
+
+Node Attribute Reference:
+
+| `<tab>` Node Attribute | Description | Type | Required |
+| --- | --- |--- | --- |
+| `id=""` | Defines the identifier that is used referencing the section. | `typeId` | Yes |
+| `translate="label"` | Defines the field that should be translatable. Usually "label". Be sure to  provide a label to make the label translatable. | `string` | No |
+| `type=""` | Defines the input type of the rendered HTML element - defaults to text. | string | No |
+| `sortOrder=""` | Defines the sort order of the section. High numbers push the section to the bottom of the page; low numbers push the section to the top. | float | No |
+| `class=""` | Adds a defined CSS class to the rendered tab HTML element. | string | No |
+
+![Magento Exam Information](./images/icon-info.png)See Section [5.3 EAV Attribute Features](#h.v4fzn8rafjf4) for available types.
+
+Node Reference
+
+| `<tab>` Node Children | Description | Type |
+| --- | --- | --- |
+| `label` | Defines the label that is displayed in the frontend. Ensure the translate="" attribute is set | string |
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Sections
+
+Node Attribute Reference:
+
+| `<section>` Node Attribute | Description | Type | Required |
+| --- | --- | --- | --- |
+| `id=""` | Defines the identifier that is used referencing the section. | `typeId` | Yes |
+| `translate="label"` | Defines the field that should be translatable. Usually "label". Be sure to  provide a label to make the label translatable. | string | No |
+| `type=""` | Defines the input type of the rendered HTML element - defaults to text. | string | No |
+| `sortOrder=""` | Defines the sort order of the section. High numbers push the section to the bottom of the page; low numbers push the section to the top. | float | No |
+| `showInDefault=""` | Show in the Default Configuration Scope | int | No |
+| `showInWebsite=""` | Show in the Website Configuration Scope | int | No |
+| `showInStore=""` | Show in the Store Configuration Scope | int | No |
+| `translate="label"` | Defines the label that is displayed in the frontend. Ensure the translate="" attribute is set | string | No |
+| `canRestore=""` | Defines if the section can be restored to default. | int | No |
+| `advanced=""` | Deprecated since 100.0.2. | bool | No |
+| `extends=""` | By providing an identifier of another section, the content of this node will extend the section that you referenced. | string | No |
+
+
+Node Reference:
+
+| `<section>` Node Children | Description | Type |
+| --- | --- | --- |
+| `label` | Defines the label that is displayed in the frontend. Ensure the translate="" attribute is set | string |
+| `class` | Adds a defined CSS class to the rendered section HTML element. | string |
+| `tab` | References the associated tab. Expects the ID of the tab. | `typeTabId` |
+| `header_css` | Neither used nor evaluated at the time of this writing. | string |
+| `resource` | References an ACL resource to provide permission settings for this section. | `typeAclResourceId` |
+| `resource` | Define one or more subgroups. | `typeGroup` |
+| `frontend_model` | Specifies a different frontend model to change the rendering and modify the output. | `typeModel` |
+| `include` | Used to include additional system_include.xsd compatible files. Usually used to structure large system.xml files. | `includeType` |
+
+![Magento Exam Information](./images/icon-info.png)See Section [5.3 EAV Attribute Features](#h.v4fzn8rafjf4) for available type models.
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Groups
+
+Node Attribute Reference:
+
+| `<group>` Node Attribute | Description | Type | Required |
+| --- | --- | --- | --- |
+| `id=""` | Defines the identifier that is used referencing the section. | `typeId` | Yes |
+| `translate="label"` | Defines the field that should be translatable. Usually "label". Be sure to  provide a label to make the label node translatable. | string | No |
+| `type=""` | Defines the input type of the rendered HTML element - defaults to text. | string | No |
+| `sortOrder=""` | Defines the sort order of the section. High numbers push the section to the bottom of the page; low numbers push the section to the top. | float | No |
+| `showInDefault=""` | Show in the Default Configuration Scope | int | No |
+| `showInWebsite=""` | Show in the Website Configuration Scope | int | No |
+| `showInStore=""` | Show in the Store Configuration Scope | int | No |
+| `canRestore=""` | Defines if the section can be restored to default. | int | No |
+| `advanced=""` | Deprecated since 100.0.2. | bool | No |
+| `extends=""` | By providing an identifier of another group, the content of this node will extend the section that you referenced. | string | No |
+
+Node Reference:
+
+| `<group>` Node Children | Description | Type |
+| --- | --- | --- |
+| `label` | Defines the label that is displayed in the frontend. Ensure the translate="" attribute is set | string |
+| `fieldset_css` | Adds one or more CSS classes to a group fieldset. | string |
+| `frontend_model` | Specifies a different frontend model class namespace to change the rendering and modify the output. | `typeModel` |
+| `clone_model` | Specifies a given model to clone fields. | `typeModel` |
+| `clone_fields` | Enabled or disabled cloning of fields. | int |
+| `help_url` | Not extensible. See below. | `typeUrl` |
+| `more_url` | Not extensible. See below. | `typeUrl` |
+| `demo_link` | Not extensible. See below. | `typeUrl` |
+| `comment` | Adds a comment below the group label. By using `<![CDATA[//]]>` HTML can be applied. | string |
+| `hide_in_single_store_mode` | Whether the group should be visible in single store mode. 1 hides the group; 0 shows the group. | int |
+| `field` | Define one or more fields that should be available under this group. | `field` |
+| `group` | Define one or more subgroups. | `unbounded` |
+| `depends` | Can be used to declare dependencies on other fields. Is used to show specific fields/groups only when a given field has a value of 1. This node expects a section/group/field. format | `depends` |
+| `attribute` | Custom attributes can be used by frontend models. Usually used to make a given frontend model more dynamic. | `attribute` |
+| `include` | Used to include additional system_include.xsd compatible files. Usually used to structure large system.xml files. | `includeType` |
+
+![Magento Exam Information](./images/icon-info.png)See Section [5.3 EAV Attribute Features](#h.v4fzn8rafjf4) for available type models.
+
+![Magento Exam Information](./images/icon-info.png)The nodes more_url, demo_url and help_url are defined by a PayPal frontend model that is only used once. These nodes are not reusable.
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Fields
+
+Node Attribute Reference:
+
+| `<field>` Node Attribute | Description | Type | Required |
+| --- | --- | --- | --- |
+| `id=""` | Defines the identifier that is used referencing the section. | `typeId` | Yes |
+| `translate="label"` | Defines the field that should be translatable. Usually "label". Be sure to  provide a label to make the label translatable. | string | No |
+| `type=""` | Defines the input type of the rendered HTML element - defaults to text. Depending on the type used, the `<source_model>` node is required. | Available Types Include: `button`, `checkbox`, `checkboxes`, `column`, `date`, `editablemultiselect`, `editor`, `fieldset`, `file`, `gallery`, `hidden`, `image`, `imagefile`, `label`, `link`, `multiline`, `multiselect`, `note`, `obscure`, `password`, `radio`, `radios`, `reset`, `select`, `submit`, `text`, `textarea`, `time`.| string | Yes |
+| `sortOrder=""` | Defines the sort order of the section. High numbers push the section to the bottom of the page; low numbers push the section to the top. | float | No |
+| `showInDefault=""` | Show in the Default Configuration Scope | int | No |
+| `showInWebsite=""` | Show in the Website Configuration Scope | int | No |
+| `showInStore=""` | Show in the Store Configuration Scope | int || No |
+| `canRestore=""` | Defines if the section can be restored to default. | int | No |
+| `advanced=""` | Deprecated since 100.0.2. | bool | No |
+| `extends=""` | By providing an identifier of another group, the content of this node will extend the section that you referenced. | string | No |
+
+Node Reference:
+| `<field>` | Node Children | Description | Type |
+| --- | --- | --- | --- |
+| `label` | `Defines the label that is displayed in the frontend.` | `string` |
+| `comment` | Adds a comment below the group label. By using <![CDATA[//]]> HTML can be applied. | `string` |
+| `tooltip` | Another possible frontend element that also can be used to describe the meaning of this field. Will be displayed as a small icon beside the field. | `string` |
+| `hint` | Displays additional information. Only available with specific frontend_model. | `string` |
+| `frontend_class` | Displays additional information. Only available with specific frontend_model. | `string` |
+| `frontend_model` | Specifies a different frontend model to change the rendering and modify the output. | `typeModel` |
+| `backend_model` | Specifies a different backend model to modify the configured values. | `typeModel` |
+| `source_model` | Specifies a different source model that provides a specific set of values. | `typeModel` |
+| `config_path` | Can be used to overwrite the generic config path of a field. | `typeConfigPath` |
+| `validate` | Define different validation rules (comma separated). Full reference list of available validation rules is listed below. | `string` |
+| `can_be_empty` | Used when type is multiselect to specify that a field can be empty. | `int` |
+| `if_module_enabled` | Used to display a field only when a given module is enabled. | `typeModule` |
+| `base_url` | Used in combination with upload_dir for file uploads. | `typeUrl` |
+| `upload_dir` | Specify a target directory for uploads. This node has additional attributes and nodes. Look them up before using this. | `typeUploadDir` |
+| `button_url` | Displays a button if button_url and button_label are specified. Usually used in combination with a custom frontend model. | `typeUrl` |
+| `button_label` | Displays a button if button_label and button_url are specified. Usually used in combination with a custom frontend model. | `string` |
+| `more_url` | Not extensible. See below. | `typeUrl` |
+| `demo_url` | Not extensible. See below. | `typeUrl` |
+| `hide_in_single_store_mode` | Whether the group should be visible in single store mode. 1 hides the group; 0 shows the group. | `int` |
+| `source_service` | Service used to populate select options. | `complexType` |
+| `options` | Not used. Potentially deprecated. | `complexType` |
+| `depends` | Can be used to declare dependencies to other fields. Is used to only show specific fields/groups when a given field has a value of 1. This node expects a section/group/field-string. | `complexType` |
+| `attribute` | Custom attributes can be used by frontend models. Usually used to make a given frontend model more dynamic. | `complexType` |
+| `requires` | Not extensible. See below. | `complexType` |
+
+![Magento Exam Information](./images/icon-info.png)See Section [5.3 EAV Attribute Features](#h.v4fzn8rafjf4) for available type models.
+
+![Magento Exam Information](./images/icon-info.png)The nodes more_url, demo_url and help_url are defined by a PayPal frontend model that is only used once. These nodes are not reusable.
+
+![Magento Exam Question](./images/icon-question.png)**How would you add a new system configuration option?**
+
+```
+<module_dir>etc/adminhtml/system.xml
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)Tabs example
+
+```xml
+<?xml version="1.0" ?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Config:etc/system_file.xsd">
+    <system>
+        <tab id="A_UNIQUE_ID" translate="label" class="a-custom-css-class-to-style-this-tab" sortOrder="10">
+            <label>A meaningful label</label>
+        </tab>
+    </system>
+</config>
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)Sections example
+```xml
+<?xml version="1.0" ?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Config:etc/system_file.xsd">
+    <system>
+        <tab id="A_UNIQUE_ID" translate="label" class="a-custom-css-class-to-style-this-tab" sortOrder="10">
+            <label>A meaningful label</label>
+        </tab>
+        <section id="A_UNIQUE_SECTION_ID" showInDefault="1" showInWebsite="0" showInStore="1" sortOrder="10" translate="label">
+            <label>A meaningful section label</label>
+            <tab>A_UNIQUE_ID</tab>
+            <resource>VENDOR_MODULE::path_to_the_acl_resource</resource>
+        </section>
+    </system>
+</config>
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)Groups example
+
+```xml
+<?xml version="1.0" ?>
+
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Config:etc/system_file.xsd">
+    <system>
+        <tab id="A_UNIQUE_ID" translate="label" class="a-custom-css-class-to-style-this-tab" sortOrder="10">
+            <label>A meaningful label</label>
+        </tab>
+        <section id="A_UNIQUE_SECTION_ID" showInDefault="1" showInWebsite="0" showInStore="1" sortOrder="10" translate="label">
+            <label>A meaningful section label</label>
+            <tab>A_UNIQUE_ID</tab>
+            <resource>VENDOR_MODULE::path_to_the_acl_resource</resource>
+            <group id="A_UNIQUE_GROUP_ID" translate="label comment" sortOrder="10" showInDefault="1" showInWebsite="0" showInStore="1">
+                <label>A meaningful group label</label>
+                <comment>An additional comment helping users to understand the effect when configuring the fields defined in this group.</comment>
+                <!-- Add your fields here. -->
+            </group>
+        </section>
+    </system>
+</config>
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)Fields example
+
+```xml
+<?xml version="1.0" ?>
+
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Config:etc/system_file.xsd">
+    <system>
+        <tab id="A_UNIQUE_ID" translate="label" class="a-custom-css-class-to-style-this-tab" sortOrder="10">
+            <label>A meaningful label</label>
+        </tab>
+        <section id="A_UNIQUE_SECTION_ID" showInDefault="1" showInWebsite="0" showInStore="1" sortOrder="10" translate="label">
+            <label>A meaningful section label</label>
+            <tab>A_UNIQUE_ID</tab>
+            <resource>VENDOR_MODULE::path_to_the_acl_resource</resource>
+            <group id="A_UNIQUE_GROUP_ID" translate="label" sortOrder="10" showInDefault="1" showInWebsite="0" showInStore="1">
+                <label>A meaningful group label</label>
+                <comment>An additional comment helping users to understand the effect when configuring the fields defined in this group.</comment>
+                <field id="A_UNIQUE_FIELD_ID" translate="label" sortOrder="10" showInDefault="0" showInWebsite="0" showInStore="1" type="select">
+                    <label>Feature Flag Example</label>
+                    <comment>This field is an example for a basic yes or no select.</comment>
+                    <tooltip>Usually these kinds of fields are used to enable or disable a given feature. Other fields might be dependent to this and will only appear if this field is set to yes.</tooltip>
+                    <source_model>Magento\Config\Model\Config\Source\Yesno</source_model>
+                </field>
+                <field id="ANOTHER_UNIQUE_FIELD_ID" translate="label" sortOrder="10" showInDefault="0" showInWebsite="0" showInStore="1" type="text">
+                    <label>A meaningful field label</label>
+                    <comment>A descriptive text explaining this configuration field.</comment>
+                    <tooltip>Another possible frontend element that also can be used to describe the meaning of this field. Will be displayed as a small icon beside the field.</tooltip>
+                    <validate>required-entry no-whitespace</validate>                    <!-- Field is required and must not contain any whitespace. -->
+                    <if_module_enabled>VENDOR_MODULE</if_module_enabled>
+                    <depends>
+                        <!-- This field will only be visible if the field with the id A_UNIQUE_FIELD_ID is set to value 1 -->
+                        <field id="A_UNIQUE_FIELD_ID">1</field>
+                    </depends>
+                </field>
+            </group>
+        </section>
+    </system>
+</config>
+```
+
+![Magento Exam Question](./images/icon-question.png)**What is the difference in this process for different option types (secret, file)?**
+
+> See the [Fields part of this section](#h.op69p944prs) to see the available types. Different Field Types require certain child nodes in order to operate.
+
+![Magento Section Chevron](./images/icon-chevron.png)Field Text
+
+> Text Fields have no requirements:
+```xml
+<field id="custom_text" translate="label" type="text" sortOrder="20" showInDefault="1" showInWebsite="1" showInStore="1">
+    <label>Custom Text</label>
+</field>
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)Field Dropdown With The Custom Source Model
+
+> Certain Select Fields require the `<source_model>` node, such like:
+
+```xml
+<field id="custom_dropdown" translate="label" type="select" sortOrder="10" showInDefault="1" showInWebsite="1" showInStore="1">
+    <label>Dropdown with custom source model example</label>
+    <source_model>MyVendor\MyModule\Model\Config\Source\Custom</source_model>
+</field>
+```
+
+> The custom `<source_model>` class will look something like:
+
+```php
+class Custom implements Magento\Framework\Option\ArrayInterface
+{
+    /** @return array */
+    public function toOptionArray()
+    {
+        return [
+            ['value' => 0, 'label' => __('Zero')],
+            ['value' => 1, 'label' => __('One')],
+            ['value' => 2, 'label' => __('Two')],
+        ];
+    }
+}
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)Field Yes/No Dropdown
+
+> Yes/No Dropdown Fields require the `<source_model>` node, such like:
+```xml
+<field id="yesno_dropdown" translate="label" type="select" sortOrder="10" showInDefault="1" showInWebsite="1" showInStore="1">
+    <label>Custom Yes/No Dropdown</label>
+    <source_model>Magento\Config\Model\Config\Source\Yesno</source_model>
+</field>
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)Field File Upload
+
+File Upload Fields require the `<backend_model> <upload_dir> <base_url>` nodes, such like:
+```xml
+<field id="logo" translate="label" type="image" sortOrder="30" showInDefault="1" showInWebsite="1" showInStore="1">
+    <label>Custom Image</label>
+    <backend_model>Magento\Config\Model\Config\Backend\Image</backend_model>
+    <upload_dir config="system/filesystem/media" scope_info="1">logo</upload_dir>
+    <base_url type="media" scope_info="1">logo</base_url>
+    <comment><![CDATA[Allowed file types: jpeg, gif, png.]]></comment>
+</field>
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)Field Dependent
+
+> Dependent Fields are available to all types, just need to define `<depends>` node such like:
+
+```xml
+<field id="depends_example" translate="label" type="text" sortOrder="40" showInDefault="1" showInWebsite="1" showInStore="1">
+    <label>Dependant text field example with validation</label>
+    <depends>
+        <field id="*/*/yesno_dropdown">1</field>
+    </depends>
+    <validate>validate-no-empty</validate>
+</field>
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)Field Textarea
+
+> Textarea Fields have no requirements:
+```xml
+<field id="custom_textarea" translate="label" type="textarea" sortOrder="50" showInDefault="1" showInWebsite="1" showInStore="1">
+    <label>Custom Textarea</label>
+</field>
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)Field Secret
+
+> Secret Fields require the `<backend_model>` & `type="obscure"` node such like:
+```xml
+<field id="custom_secret" type="obscure" translate="label" sortOrder="70" showInDefault="1" showInWebsite="1" showInStore="1">
+    <label>Custom Secret Field</label>
+    <backend_model>Magento\Config\Model\Config\Backend\Encrypted</backend_model>
+</field>
+```
+![Magento Exam Information](./images/icon-info.png)`type="obscure"` hides the field's value from the frontend, but the information from it will still be saved as plain text. Setting `Magento\Config\Model\Config\Backend\Encrypted` as a backend model allows to encrypt the data in the database.
+
+![Magento Exam Information](./images/icon-info.png)Most of the source models are located in `Magento\Config\Model\Config\Source` and backend models are located in `Magento\Config\Model\Config\Backend`.
+
+![Magento Exam Question](./images/icon-question.png)**Setting Default Value**
+
+> To set default value for any of the custom settings, create a file:
+```
+<module_dir>/etc/config.xml
+```
+
+> The format goes: section/group/field
+
+Example:
+```xml
+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Store:etc/config.xsd">
+    <default>
+        <custom_section>
+            <general>
+                <yesno_dropdown>1</enable>
+                <custom_text>Test Value</display_text>
+            </general>
+        </custom_section>
+    </default>
+</config>
+```
+
+![Magento Exam Question](./images/icon-question.png)**Describe system configuration data retrieval. How do you access system configuration options programmatically?**
+
+> Programmatically requesting system configuration options are available from class: `Magento\Framework\App\Config\ScopeConfigInterface`
+>
+> Usually within a custom module this resides within a Helper class' $this->scopeConfig property which extends class: `Magento\Framework\App\Helper\AbstractHelper`
+
+Example:
+
+```php
+<?php
+
+namespace MyVendor\MyModule\Helper;
+
+use Magento\Framework\App\Helper\AbstractHelper;
+use Magento\Store\Model\ScopeInterface;
+
+class Config extends AbstractHelper
+{
+    const XML_PATH_VENDOR = 'myvendor/';
+
+    /** @return string */
+    public function getTestValue(): string
+    {
+        return (string) $this->scopeConfig->getValue(
+            static::XML_PATH_VENDOR . 'settings/test_value',
+            ScopeInterface::SCOPE_STORE
+        );
+    }
+}
+
+```
+
+6.4 Utilize ACL to set menu items and permissions
+-------------------------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**Describe how to set up a menu item and permissions.**
+
+> Access Control List (ACL) rules allow an admin to limit the permissions of users in Magento. For example, you can use ACL rules to authorize the users to access menus, controllers, API endpoints and conditionally render layout blocks.
+>
+> ACL is defined in:
+>
+> `<module_dir>/etc/adminhtml/acl.xml`
+
+Example:
+
+```xml
+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Acl/etc/acl.xsd">
+    <acl>
+        <resources>
+            <resource id="Magento_Backend::admin">
+                <resource id="Vendor_MyModule::menu" title="Custom Menu" sortOrder="10">
+                    <resource id="Vendor_MyModule::create" title="Create" sortOrder="50" />
+                    <resource id="Vendor_MyModule::delete" title="Delete" sortOrder="100" />
+                    <resource id="Vendor_MyModule::view" title="View" sortOrder="150">
+                        <resource id="Vendor_MyModule::view_additional" title="View Additional Information" sortOrder="10" />
+                    </resource>
+                </resource>
+            </resource>
+        </resources>
+    </acl>
+</config>
+```
+
+| `<resource>` Attribute | Description |
+| --- | --- |
+| `id` | Unique string. Should be in the format `Vendor_ModuleName::resourceName` |
+| `title` | Title which is displayed in the menu bar |
+| `sortOrder` | Position in which menu is displayed |
+
+![Magento Exam Question](./images/icon-question.png)**How would you add a new menu item in a given tab?**
+
+> Using declarative schema in menu.xml you can add items to Magento's main left navigation of the admin.
+>
+> Menu Items are defined in:
+>
+> `<module_dir>etc/adminhtml/menu.xml`
+
+Example:
+
+```xml
+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Backend:etc/menu.xsd">
+    <menu>
+        <add id="Vendor_MyModule::menu" title="Custom Menu" module="Vendor_MyModule" sortOrder="10" resource="Vendor_MyModule::menu"/>
+        <add id="Vendor_MyModule::create" title="Create" module="Vendor_MyModule" sortOrder="10" parent="Vendor_MyModule::menu" action="custommenu/create/index" resource="Vendor_MyModule::create"/>
+        <add id="Vendor_MyModule::delete" title="Delete" module="Vendor_MyModule" sortOrder="20" parent="Vendor_MyModule::menu" action="custommenu/delete/index" resource="Vendor_MyModule::delete"/>
+        <add id="Vendor_MyModule::view" title="View" module="Vendor_MyModule" sortOrder="30" parent="Vendor_MyModule::menu" action="custommenu/view/index" resource="Vendor_MyModule::view"/>
+    </menu>
+</config>
+```
+
+| `<add>` Attribute | Description |
+| --- | --- |
+| `id` | Unique string. Should be in the format: `Vendor_ModuleName::resourceName` |
+| `title` | Title which is displayed in menu bar |
+| `module` | Module which containing the current menu |
+| `sortOrder` | Position in which menu to be displayed |
+| `parent` | The another menu which is parent of current menu |
+| `action` | Url of the page which needs to be displayed after clicking the menu. It should be in following format: `front_name/controller_path/action` |
+| `resource` | ACL rule to restrict the access |
+
+![Magento Exam Question](./images/icon-question.png)**How would you add a new tab in the Admin menu?**
+
+![Magento Section Chevron](./images/icon-chevron.png) Primary Sidebar Navigation Menu
+
+> Define an <add> node WITHOUT a `parent=""` attribute in:
+>
+> `<module_dir>/etc/adminhtml/menu.xml`
+
+[More info on how to define this above](#h.gk6g5dbgvggm).
+
+![Magento Exam Information](./images/icon-info.png)In contrast, define a `parent=""` attribute if you'd like your menu item to appear under a sub-menu / tab.
+
+![Magento Section Chevron](./images/icon-chevron.png)System Stores Configuration Tab
+
+> If you'd rather your new settings be in a Tab format under:
+>
+> **Admin > Stores > Configuration**
+>
+> Then you will need to configure a new [system.xml](#h.op69p944prs)
+> Under and existing tab, you need to specify the existing tab's ID such as:
+>
+> `<tab>general</tab>`
+>
+> Otherwise you will need to create your own `<tab>`. [See Section 6.3 for more detail](#h.op69p944prs) on how to achieve this.
+
+![Magento Exam Question](./images/icon-question.png)**How do menu items relate to ACL permissions?**
+
+> Using the `resource=""` attribute within the `<add>` nodes determine the resource each action accesses.
+>
+> Defined in:
+>
+> `<module_dir>/etc/adminhtml/menu.xml`
+>
+> File will render your menu items hidden from unauthorized users. More info on how to define this above.
+
+![Magento Exam Question](./images/icon-question.png)**Describe how to check for permissions in the permissions management tree structures. How would you add a new user with a given set of permissions?**
+
+> ACL permissions are viewed within the admin path:
+>
+> **Admin > System > Permissions > User Roles**
+>
+> **Admin > System > Permissions > All Users**
+>
+> Here contains all the available roles, their permissions and allows us to create new users or modify the current users, as well as assign user roles.
+>
+> When defining a new user with a custom ACL:
+>
+> After clicking the Add New Role button, enter values for Role Name and Your Password. Then, click a Role Resources tab and select Resource Access as Custom. You should see any custom ones here.
+
+![Magento Exam Question](./images/icon-question.png)**How can you do that programmatically?**
+
+![Magento Section Chevron](./images/icon-chevron.png)Within an action Controller
+
+> To restrict permissions to actions with ACL, override `_isAllowed` method or `ADMIN_RESOURCE` constant in the class of this action. The following is available to those actions extending `Magento\Backend\App\AbstractAction`:
+
+```php
+protected function _isAllowed()
+{
+    return $this->_authorization->isAllowed('MyVendor_MyModule::config');
+}
+```
+
+> OR, define a constant in your action Controller:
+
+```php
+const ADMIN_RESOURCE = 'MyVendor_MyModule::config';
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)Creating a new User Role
+
+> Inject `Magento\Authorization\Model\RoleFactory` & `Magento\Authorization\Model\RulesFactory`
+
+```php
+$role = $this->roleFactory->create();
+$role->setParentId(0)
+    ->setTreeLevel(1)
+    ->setSortOrder(1)
+    ->setRoleType(Group::ROLE_TYPE)
+    ->setUserId(0)
+    ->setUserType(UserContextInterface::USER_TYPE_ADMIN)
+    ->setRoleName('Example Administrator');
+
+/** @var \Magento\Authorization\Model\Rules $rule */
+$rule = $this->rulesFactory->create();
+$rule->setRoleId($role->getId())
+    ->setResourceId($this->rootResource->getId())
+    ->setPrivilegies(null)
+    ->setPermission('allow');
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)Creating a new User
+
+Inject class `Magento\User\Model\UserFactory`:
+
+```php
+$adminUser = $this->userFactory->create();
+$adminUser->setRoleId(ROLE_ID)
+    ->setEmail('admin' . $i . '@example.com')
+    ->setFirstName('Firstname')
+    ->setLastName('Lastname')
+    ->setUserName('admin' . $i)
+    ->setPassword('123123q')
+    ->setIsActive(1);
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)Via CLI
+
+```bash
+php bin/magento admin:user:create
+```
\ No newline at end of file
diff --git a/7. Customizing the Catalog/1. Demonstrate ability to use products and product types.md b/7. Customizing the Catalog/1. Demonstrate ability to use products and product types.md
deleted file mode 100644
index e103226..0000000
--- a/7. Customizing the Catalog/1. Demonstrate ability to use products and product types.md	
+++ /dev/null
@@ -1,174 +0,0 @@
-# Demonstrate ability to use products and product types
-
-## Identify/describe standard product types (simple, configurable, bundled, etc.).
-
-Product type model - [Magento\Catalog\Model\Product\Type\AbstractType](https://github.com/magento/magento2/blob/2.2-develop/app/code/Magento/Catalog/Model/Product/Type/AbstractType.php)
-
-7 product types:
-
-- [*virtual*](https://github.com/magento/magento2/blob/2.2-develop/app/code/Magento/Catalog/Model/Product/Type/Virtual.php)
-
-    Not tangible products - services, memberships, warranties, and subscriptions. No weight, can't be shipped.
-
-- [*simple*](https://github.com/magento/magento2/blob/2.2-develop/app/code/Magento/Catalog/Model/Product/Type/Simple.php)
-
-    Single SKU, has weight and can be shipped.
-    
-- [*downloadable*](https://github.com/magento/magento2/blob/2.2-develop/app/code/Magento/Downloadable/Model/Product/Type.php)
-
-    Same as virtual + downloadable links
-    
-- [*configurable*](https://github.com/magento/magento2/blob/2.2-develop/app/code/Magento/ConfigurableProduct/Model/Product/Type/Configurable.php)
-
-    Add 1 composite product, consisting of 1 selected variation. All options are connected.
-    Child product inventory tracked separately.
-    
-- [*grouped*](https://github.com/magento/magento2/blob/2.2-develop/app/code/Magento/GroupedProduct/Model/Product/Type/Grouped.php)
-
-    Groups multiple products on same page. Customer can buy all of some of them, edit qty.
-    After adding to cart, they are separate, same as if you added each of them one by one.
-
-- [*bundle*](https://github.com/magento/magento2/blob/2.2-develop/app/code/Magento/Bundle/Model/Product/Type.php)
-
-    Add 1 composite product, consisting of many selected variations, options independent.
-    SKU dynamic/fixed, weight dynamic/fixed, price dynamic/fixed. Each qty x total qty.
-    Inventory is tracked separately for each child.
-    
-- *gift card (Commerce edition)*
-
-    Like downloadable, purchase gift card code instead of link.
-    Can be virtual/physical/both. Thus can be shipped.
-    
-## product_types.xml - maximum configuration:
-```xml
-<type name="mytype" label="My Type Product" modelInstance="..." composite="false" isQty="false" canUseQtyDecimals="true" indexPriority="10" sortOrder="10">
-    <priceModel instance="...\Model\Product\Type\Mytype\Price" />
-    <indexerModel instance="...\Model\ResourceModel\Product\Indexer\Price\Mytype" />
-    <stockIndexerModel instance="...\Model\ResourceModel\Indexer\Stock\Mytype" />
-    <customAttributes>
-        <attribute name="is_real_product" value="true"/>
-        <attribute name="refundable" value="true/false"/>
-        <attribute name="taxable" value="true"/>
-        <attribute name="is_product_set" value="false"/>
-    </customAttributes>
-    <allowedSelectionTypes>
-        <type name="simple" />
-        <type name="virtual" />
-    </allowedSelectionTypes>
-</type>
-<composableTypes>
-  <type name="simple"/>
-  <type name="virtual"/>
-  <type name="downloadable"/>
-</composableTypes>
-```
-
-### How would you obtain a product of a specific type?
-
-Product type code is stored in catalog_product_entity.type_id. Thus, we can use collection:
-`$productCollection->addFieldToFilter('type_id', 'simple');`
-
-### What tools (in general) does a product type model provide?
-
-*_prepareProduct* - given add to cart request, returns product items that will be converted to quote items
-
-When product is added to cart:
-- [\Magento\Checkout\Controller\Cart\Add::execute](https://github.com/magento/magento2/blob/2.2-develop/app/code/Magento/Checkout/Controller/Cart/Add.php#L80)
-- [\Magento\Checkout\Model\Cart::addProduct](https://github.com/magento/magento2/blob/2.2-develop/app/code/Magento/Checkout/Model/Cart.php#L354)
-- [\Magento\Quote\Model\Quote::addProduct](https://github.com/magento/magento2/blob/2.2-develop/app/code/Magento/Quote/Model/Quote.php#L1583)
-- `$cartCandidates = $product->getTypeInstance()->prepareForCartAdvanced($request, $product, $processMode);`
-- [`prepareForCartAdvanced`](https://github.com/magento/magento2/blob/2.2-develop/app/code/Magento/Catalog/Model/Product/Type/AbstractType.php#L455) simply calls [`typeInstance._prepareProduct`](https://github.com/magento/magento2/blob/2.2-develop/app/code/Magento/Catalog/Model/Product/Type/AbstractType.php#L371)
-- type analyzes request and initializes one or many product items
-- quote converts product items to quote_items
-
-Standard types:
-- `simple._prepareProduct` - just returns [product]. one record will be saved in quote_item
-- `configurable._prepareProduct` - prepares and returns [parentProduct, childProduct].
-  Configures parent, configures child, then adds some useful linking info to their custom options.
-
-  * adds parent configurable product normally
-  * based on param `super_attribute` selections (color=red, size=XL), loads sub product
-  * parentProduct.setCustomOptions:
-    + `attributes = {color: 12, size: 35}`, 
-    + `product_qty_{$subProduct.id} = 1`
-    + `simple_product = $subProduct`
-    + recursively calls subProduct.getTypeInstance._prepareProduct. this will configure child product as well
-  * subProduct.setCustomOption(`parent_product_id`, ID)
-- `grouped._prepareProduct`
-  * loads sub products individually from `catalog_product_link` by type id LINK_TYPE_GROUPED = 3
-  * subProduct[].getTypeInstance._prepareProduct
-  * some meta info is added to custom options:
-    + `product_type = 'grouped'`
-  * all configured products are returned as separate items, not linked to any parent
-- `bundle._prepareProduct` - [parentProduct, selectedChild1, ..., selectedChildN]
-- `downloadable._prepareProduct` - same as simple, plus additionally generates product links
-  * shows error if required links not selected
-  * product.setCustomOption(`downloadable_link_ids`, '1,2,...')
-
-`_prepareProduct` is mostly where product type customization are placed. Here you analyze request (`$_POST` values),
-validate input, can set prices, custom option.
-Primary goal is to return configured products with custom options (`product.setCustomOption`).
-Each product will be converted to `quote_item` records, custom options will be converted to `quote_item_option` records.
-
-
-*processBuyRequest()*
-
-Convert buyRequest back to options to configure when you added product to cart and click Configure.
-
-
-*checkProductBuyState()*
-
-Check product has all required options. read product.getCustomOption, throws exception on error.
-Used by quote_item.checkData() - checks if product in cart is healthy.
-
-
-*getOrderOptions()*
-
-Prepare additional options/information for order item which will be created from this product.
-
-- product_calculations - parent/child
-- shipment_type - together/separately
-
-
-*getSku()*, *getOptionSku()*
-
-Glues SKU parts for custom options, bundle selections etc.
-
-
-*getRelationInfo()* - [table, parent_field_name, child_field_name, where]
-
-Used in:
-- fulltext search to get attributes of product+children
-- product flat indexer - insert children into flat
-
-
-*getWeight()*
-
-- configurable product used simple product's weight
-- bundle product composes sum weight of components (if weight type dynamic)
-
-
-*isSalable()*
-
-- by default true if product status is enabled
-- data['is_salable'] can force not salable (data attribute set by inventory from stock index?)
-- configurable - at least one enabled child product must be in stock
-- bundle - all required options are salable
-- downloadable - must have links
-
-
-*processBuyRequest()*
-
-Used for setting product preconfigured values - color, size, bundle selections - when
-configuring added product.
-
-[Helper\Product.prepareProductOptions](https://github.com/magento/magento2/blob/2.2-develop/app/code/Magento/Catalog/Helper/Product.php#L485):
-```php
-$optionValues = $product->processBuyRequest($buyRequest);
-  // $type->processBuyRequest
-$optionValues->setQty($buyRequest->getQty());
-$product->setPreconfiguredValues($optionValues);
-```
-
-- configurable - assigns super_attribute selection.
-- gift card - assigns amount, messages, emails etc. - all form data from remembered buy request.
diff --git a/7. Customizing the Catalog/2. Describe price functionality.md b/7. Customizing the Catalog/2. Describe price functionality.md
deleted file mode 100644
index a6ebfa8..0000000
--- a/7. Customizing the Catalog/2. Describe price functionality.md	
+++ /dev/null
@@ -1,318 +0,0 @@
-# Describe price functionality
-
-## Identify the basic concepts of price generation in Magento.
-
-*Terms:*
-- price info factory - creates *price info* and passes new *price collection* for specific product instance and qty
-- *price info* - holds *adjustment collection* and *price collection*. same across all product types
-- *price collection* - holds price pool
-- *price pool* - holds price interfaces for every type of price - regular, special, final etc.
-  Class is same, but a lot of copies are created by di configuration.
-- *adjustment collection* - holds *adjustment pool* and adjustment codes - `tax`, `wee`, `wee_tax`
-- *adjustment pool* - holds adjustments by code - `tax` sort 20, `wee` sort 25, `wee_tax` sort 35
-- *price interface* - holds float value in display currency, price amount obj., can return custom amount without specific adjustments
-- *amount interface* - in display currency. base, full amount, adjustments
-
-What's `wee_tax`:
-- fixed product tax (FPT) can be configured to be taxed
-- tax percentage over fixed tax
-
-Flow:
-- product implements Pricing\SaleableInterface
-- product.getPriceInfo
-- \Magento\Catalog\Model\Product\Type::getPriceInfo
-- Pricing\PriceInfo\Factory::create - by product instance and qty
-  * di injectable type configurations: product_type_id => [infoClass, prices]
-  * creates *price collection* = [$type_id]['prices']
-    + separate *copy* of `Pricing\Price\Collection` with according *copy* of `Pricing\Price\Pool` with
-      separate set of price info classes by type - regular, final etc.
-    + ALL product types have personal collection and pool instance
-  * creates *price info* = `Pricing\PriceInfo\Base`
-    + MOST product types use SAME instance `Pricing\PriceInfo\Base` with default `Pricing\Adjustment\Collection`
-    + Only bundle product holds custom *copy* with custom instance of `Adjustment\Collection` - but has NO changes.
-      So it's just a separate copy.
-
-- Pricing\PriceInfoInterface
-- Pricing\Price\Collection - separate pool by product type
-- Pricing\Price\Pool - iterate/access by code prices. A lot of pools per product type. `target` argument means inherit prices from other type
-  * Magento\Catalog\Pricing\Price\Pool
-  * Magento\Bundle\Pricing\Price\Pool
-  * Magento\ConfigurableProduct\Pricing\Price\Pool
-  * Magento\Downloadable\Pricing\Price\Pool
-  * Magento\GroupedProduct\Pricing\Price\Pool
-  * Magento\GiftCard\Pricing\Price\Pool
-
-## product type -> price collection -> price pool -> prices:
-- `default` -> Magento\Catalog\Pricing\Price\Collection -> Magento\Catalog\Pricing\Price\Pool:
-  * regular_price = Magento\Catalog\Pricing\Price\RegularPrice
-  * final_price = Magento\Catalog\Pricing\Price\FinalPrice
-  * tier_price = Magento\Catalog\Pricing\Price\TierPrice
-  * special_price = Magento\Catalog\Pricing\Price\SpecialPrice
-  * base_price = Magento\Catalog\Pricing\Price\BasePrice
-  * custom_option_price = Magento\Catalog\Pricing\Price\CustomOptionPrice
-  * configured_price = Magento\Catalog\Pricing\Price\ConfiguredPrice
-  * wishlist_configured_price = Magento\Catalog\Pricing\Price\ConfiguredPrice
-  * catalog_rule_price = Magento\CatalogRule\Pricing\Price\CatalogRulePrice
-  * (staging) catalog_rule_price = Magento\CatalogRuleStaging\Pricing\Price\CatalogRulePrice
-
-- `downloadable` -> Magento\Downloadable\Pricing\Price\Collection -> Magento\Downloadable\Pricing\Price\Pool:
-  * link_price = Magento\Downloadable\Pricing\Price\LinkPrice
-  * wishlist_configured_price = Magento\Wishlist\Pricing\ConfiguredPrice\Downloadable
-  * _inherit rest from_ `default`
-
-- `configurable` -> Magento\ConfigurableProduct\Pricing\Price\Collection -> Magento\ConfigurableProduct\Pricing\Price\Pool:
-  * regular_price = Magento\ConfigurableProduct\Pricing\Price\ConfigurableRegularPrice
-  * final_price = Magento\ConfigurableProduct\Pricing\Price\FinalPrice
-  * wishlist_configured_price = Magento\Wishlist\Pricing\ConfiguredPrice\ConfigurableProduct
-  * _inherit rest from_ `default`
-
-- `bundle` -> Magento\Bundle\Pricing\Price\Collection -> Magento\Bundle\Pricing\Price\Pool:
-  * regular_price = Magento\Bundle\Pricing\Price\BundleRegularPrice
-  * final_price = Magento\Bundle\Pricing\Price\FinalPrice
-  * tier_price = Magento\Bundle\Pricing\Price\TierPrice
-  * special_price = Magento\Bundle\Pricing\Price\SpecialPrice
-  * custom_option_price = Magento\Catalog\Pricing\Price\CustomOptionPrice
-  * base_price = Magento\Catalog\Pricing\Price\BasePrice
-  * configured_price = Magento\Bundle\Pricing\Price\ConfiguredPrice
-  * bundle_option = Magento\Bundle\Pricing\Price\BundleOptionPrice
-  * catalog_rule_price = Magento\CatalogRule\Pricing\Price\CatalogRulePrice
-  * wishlist_configured_price = Magento\Bundle\Pricing\Price\ConfiguredPrice
-
-- `grouped` => Magento\GroupedProduct\Pricing\Price\Collection -> Magento\GroupedProduct\Pricing\Price\Pool:
-  * final_price = Magento\GroupedProduct\Pricing\Price\FinalPrice
-  * configured_price = Magento\GroupedProduct\Pricing\Price\ConfiguredPrice
-  * wishlist_configured_price = Magento\GroupedProduct\Pricing\Price\ConfiguredPrice
-  * _inherit rest from_ `default`
-
-- `giftcard` => Magento\GiftCard\Pricing\Price\Collection => Magento\GiftCard\Pricing\Price\Pool:
-  * regular_price = Magento\Catalog\Pricing\Price\RegularPrice
-  * final_price = Magento\GiftCard\Pricing\Price\FinalPrice
-  * tier_price = Magento\Catalog\Pricing\Price\TierPrice
-  * special_price = Magento\Catalog\Pricing\Price\SpecialPrice
-  * msrp_price = Magento\Msrp\Pricing\Price\MsrpPrice
-  * custom_option_price = Magento\Catalog\Pricing\Price\CustomOptionPrice
-  * base_price = Magento\Catalog\Pricing\Price\BasePrice
-  * configured_price = Magento\GiftCard\Pricing\Price\ConfiguredPrice
-  * bundle_option = Magento\Bundle\Pricing\Price\BundleOptionPrice
-  * wishlist_configured_price = Magento\GiftCard\Pricing\Price\ConfiguredPrice
-
-Default *regular price* example:
-- getValue - *product.getPrice*, convert to display currency. This is raw float value without adjustments
-- getAmount = Pricing\Adjustment\Calculator::getAmount:
-  * priceInfo.getAdjustments
-  * adjustment can be included in base price, included in display price
-  * if included in base price:
-    + extractAdjustment - get base price without adjustment.
-    + applyAdjustment - add adjustment back
-  * if included in display price:
-    + applyAdjustment - add adjustment over base price
-
-Default *final price* example:
-- `final_price` delegates calculation to `base_price`
-- gets all prices info, checks implementing `Pricing\Price\BasePriceProviderInterface`
-  * regular_price, catalog_rule_price, special_price, tier_price
-- takes min value
-
-And so on. Most classes customize PriceInterface `getValue`, while `getAmount` and adjustment adding is the same.
-
-*Adjustment*:
-- isIncludedInBasePrice
-  * tax = true if admin prices are including tax
-  * weee = false, they are always added on top of base price
-- isIncludedInDisplayPrice
-  * tax = display prices incl. tax
-- *extractAdjustment* - return base price without adjustment (taxes)
-- *applyAdjustment* - base price + adjustment
-- getSortOrder
-
-### How would you identify what is composing the final price of the product?
-`default` final price:
-- `final_price` delegates calculation to `base_price`
-- gets all prices info, checks implementing `Pricing\Price\BasePriceProviderInterface`
-  * regular_price, catalog_rule_price, special_price, tier_price
-- takes min value
-
-`configurable` final price:
-- price resolver interface \Magento\ConfigurableProduct\Pricing\Price\PriceResolverInterface
-- ConfigurableFinalPriceResolver -> Magento\ConfigurableProduct\Pricing\Price\ConfigurablePriceResolver
-- gets products with lowest prices by *lowest price options provider*, one lowest product from each type:
-  * base price
-  * tier price
-  * index price
-  * catalog rule price
-- when selecting, lowest product is also processed by *select processors*:
-  * status enabled
-  * assigned website match
-  * in stock (`cataloginventory_stock_status`) -- when hide out of stock
-  * in stock -- when show out of stock (?)
-- get final price of each individual lowest product
-- configurable final price is lowest of their values
-
-`grouped` final price:
-- lowest final price of all individual products in group
-
-`bundle` final price:
-- same as `default` final price (min of classes implementing interface `BasePriceProviderInterface`)
-  plus `bundle_option` price - check price type fixed/dynamic, all required salable options * qty
-
-`giftcard` final price:
-- first giftcard amount
-
-### How can you customize the price calculation process?
-1. Create price adjustment:
-- Implements Pricing\Adjustment\AdjustmentInterface
-- DI configuration:
-
-    ```xml
-    <type name="Magento\Framework\Pricing\Adjustment\Collection">
-        <arguments>
-            <argument name="adjustments" xsi:type="array">
-                <item name="somecode" xsi:type="const">Custom\Module\Pricing\Adjustment::ADJUSTMENT_CODE</item>
-            </argument>
-        </arguments>
-    </type>
-    ```
-    ```xml
-    <type name="Magento\Framework\Pricing\Adjustment\Pool">
-        <arguments>
-            <argument name="adjustments" xsi:type="array">
-                <item name="somecode" xsi:type="array">
-                    <item name="className" xsi:type="string">Custom\Module\Pricing\Adjustment</item>
-                    <item name="sortOrder" xsi:type="string">40</item>
-                </item>
-            </argument>
-        </arguments>
-    </type>
-    ```
-- implement isIncludedInBasePrice, isIncludedinDisplayPrice, extractAdjustment, applyAdjustment
-
-1. Register some new price type with `default` price pool, implement interface `Pricing\Price\BasePriceProviderInterface`.
-My new price can influence final price if returns lowest price.
-1. Create plugin over necessary native price classes, e.g. around getValue
-1. Replace price class via DI for specific virtual pool, e.g.
-```xml
-<virtualType name="Magento\Bundle\Pricing\Price\Pool">
-    <arguments>
-        <argument name="prices" xsi:type="array">
-            <item name="regular_price" xsi:type="string">Custom\Module\Pricing\Price\BundleRegularPrice</item>
-        </argument>
-    <arguments>
-</virtualType>
-```
-1. Replace price class via DI preference for specific class.
-
-
-## Describe how price is rendered in Magento
-
-Terms:
-- *global render* - shared block `Magento\Framework\Pricing\Render` declared in `default.xml` layout.
-  Data-arguments contain global defaults.
-- *local render* - specific instance block `Magento\Catalog\Pricing\Render` to render specific price
-  in designated location. Can be multiple on the same page. Its block arguments overwrite arguments
-  from *global renderer*. At least must set argument `price_type_code`.
-- *price layout* - simple wrapper that holds separate layout instance and renders only one layout handle `catalog_product_prices`.
-- *renderer pool* - shared block `Pricing\Render\RendererPool` defined in `catalog_product_prices.xml`.
-  Data-arguments describe price box *class*, *template*, *amount renderer* and *adjustment render* for each
-  combination of *product type* and *price type*, or defaults when not customized.
-- *price box* - `Pricing\Render\PriceBoxInterface` - renders template, can render multiple prices like old price and special price
-- *amount render* - `Pricing\Render\Amount` - renders one specific price inside price box - *display value* and *adjustments html*
-- *adjustment render* - `Pricing\Render\AbstractAdjustment` - whatever custom adjustment markup. has access to amount render and amount
-
-
-- include *local render* block in layout:
-```xml
-<block class="Magento\Catalog\Pricing\Render" name="product.price.final">
-    <arguments>
-        <argument name="price_render" xsi:type="string">product.price.render.default</argument>
-        <argument name="price_type_code" xsi:type="string">final_price</argument>
-        <argument name="zone" xsi:type="string">item_view</argument>
-        <argument name="display_msrp_help_message" xsi:type="string">1</argument>
-        <argument name="id_suffix_some" xsi:type="string">copy-</argument>
-    </arguments>
-</block>
-```
-- gets layout block by name in `price_render`
-- *global render* - block `product.price.render.default` = Framework\Pricing\Render
-  is declared in `default` handle with *default arguments* - present for all pages.
-```xml
-<block class="Magento\Framework\Pricing\Render" name="product.price.render.default">
-    <arguments>
-        <argument name="price_render_handle" xsi:type="string">catalog_product_prices</argument>
-        <argument name="use_link_for_as_low_as" xsi:type="boolean">true</argument>
-        <!-- set "override" configuration settings here -->
-    </arguments>
-</block>
-```
-- *global render*.`_prepareLayout`:
-  * has *price layout* - mini-copy of layout. it had only one block *renderer pool*, every product type add own arguments by type.
-  * priceLayout.addHandle from arguments `price_render_handle`, by default `catalog_product_prices`
-  * priceLayout.loadLayout - full layout processing - load, generateXml, generateElements.
-- *local render*._toHtml - could be cached
-- *local arguments* are merged with default arguments, additional argument `render_block` = *local render*
-- *global render*.render
-- get *renderer pool* from *price layout* (`catalog_product_prices` handle):
-- Pricing\Render\RendererPool::createPriceRender by *product type* and requested *price code*:
-  Searches `renderer_class` in data arguments by patterns:
-  * `$type/prices/$priceCode/render_class`
-  * `$type/default_render_class`
-  * `default/prices/$priceCode/render_class`
-  * `default/default_render_class`
-- creates new found *price box* block instance of `Pricing\Render\PriceBoxRenderInterface`
-- finds and sets template from data arguments by patterns:
-  * `$type/prices/$priceCode/render_template`
-  * `$type/default_render_template`
-  * `default/prices/$priceCode/render_template`
-  * `default/default_render_template`
-- all *price boxes* are cached: `store-template-baseUrl-template-[price_id_prefix.productId.price_id_suffix]-priceCode`
-
-E.g. `simple` product type renders `final_price` price box:
-- price box class `Magento\Catalog\Pricing\Render\FinalPriceBox`
-- template `Magento_Catalog::product/price/final_price.phtml`
-- if has special price, shows 2 prices - '.special-price' and '.old-price':
-
-  has special = regular price (product.getPrice) < final price (lowest of regular_price, catalog_rule_price, special_price, tier_price)
-
-- shows as low as if applicable
-- amount = finalPriceInfo.getAmount() = price.getValue + adjustments in display currency
-- price box.renderAmount(amount)
-- price box.getAmountRender
-- renderer pool.createAmountRender - from data-arguments by patterns:
-  * `$type/prices/$priceCode/amount_render_class`
-  * `$type/default_amount_render_class`
-  * `default/prices/$priceCode/amount_render_class`
-  * `default/default_amount_render_class`
-- amount render template:
-  * `$type/prices/$priceCode/amount_render_template`
-  * `$type/default_amount_render_template`
-  * `default/prices/$priceCode/amount_render_template`
-  * `default/default_amount_render_template`
-
-E.g. `simple` product renders `final_price` amount:
-- amount render class `Pricing\Render\Amount`
-- amount render template `Magento_Catalog::product/price/amount/default.phtml` - '.price-container'
-- amount render.getDisplayValue = amount.getValue() = price.getValue() + adjustments
-- amount render.getAdjustmentsHtml
-  * renderer pool.getAdjustmentRenders - finds adjustment = [class, template] by patterns - can be multiple!
-    + `$type/adjustments/$priceCode`
-    + `$type/adjustments/default`
-    + `default/adjustments/$priceCode`
-    + `default/adjustments/default`
-    E.g. \Magento\Tax\Pricing\Render\Adjustment with `Magento_Tax::pricing/adjustment.phtml`
-- amount render.getAdjustments(array)
-  * can suppress adjustments by setting data `skip_adjustments`
-  * set css classes from adjustment codes
-  * check that adjustment applies: amount.getAdjustmentAmount(code)
-  * adjustment render.render
-  * adjustment render.apply - must implement abstract method, e.g. call `$this->toHtml`.
-    Can set back data-attributes to amount render, e.g. classes and labels.
-
-### How would you render price in a given place on the page
-Include new copy block type `Magento\Catalog\Pricing\Render`, pass required value for `price_type_code` argument.
-
-### ... and how would you modify how the price is rendered?
-- use data-arguments to customize data for *price box*, *amount renders* and *adjustment renders*:
-  * css_classes, price_id, price_id_prefix, price_id_suffix
-- create layout handle `catalog_product_prices.xml`, reference block `render.product.prices` and customize arguments.
-  * (product type/price type or default type) *price box* class and template, *amount render* class and template
-  * (product type/price type or default type) specific adjustment class and template
-  
diff --git a/7. Customizing the Catalog/3. Demonstrate ability to use and customize categories.md b/7. Customizing the Catalog/3. Demonstrate ability to use and customize categories.md
deleted file mode 100644
index 3f5497d..0000000
--- a/7. Customizing the Catalog/3. Demonstrate ability to use and customize categories.md	
+++ /dev/null
@@ -1,86 +0,0 @@
-# Demonstrate ability to use and customize categories
-
-## Describe category properties and features.
-
-Category features:
-- can be anchored/non-anchored. When anchored, all products from subcategories "bubble up" and show up in
-  the category listing even when _not assigned_ explicitly.
-- include in menu switch
-- display type - products only, cms block only, both
-- you can assign direct category products and set their individual positions. Directly assigned products
-  always show before "bubbled up" for anchor.
-
-## How do you create and manage categories?
-- as always, prefer using repository over directly saving model
-- [Magento\Catalog\Model\CategoryRepository](https://github.com/magento/magento2/blob/2.2-develop/app/code/Magento/Catalog/Model/CategoryRepository.php)
-- [Magento\Catalog\Model\CategoryManagement](https://github.com/magento/magento2/blob/2.2-develop/app/code/Magento/Catalog/Model/CategoryManagement.php) - getTree, move, getCount
-- [category.move](https://github.com/magento/magento2/blob/2.2-develop/app/code/Magento/Catalog/Model/Category.php#L384)(newParent, afterId) -- old approach
-
-## [Category model](https://github.com/magento/magento2/blob/2.2-develop/app/code/Magento/Catalog/Model/Category.php) - few changes since M1
-- getTreeModel, getTreeModelInstance
-- move - event `catalog_category_move_before`, `catalog_category_move_after`, event `category_move`,
-  indexer.reindexList, clean cache by tag
-- getProductCollection
-- getStoreIds
-
-- getPathIds, getLevel
-- getParentId, getParentIds - without self ID
-- getParentCategory
-- getParentDesignCategory - Category
-- isInRootCategoryList
-
-- getAllChildren - = by default joined ids ("2,3,4...") + parent id, recursive, only active
-- getChildren - joined ids ("2,3,4..."), only immediate, only active
-- hasChildren - recursive, only active
-- getAnchorsAbove - array of ids - parents that are anchor
-- getProductCount - only directly assigned, all
-
-- getCategories - tree|collection. recursive, only active, only include_in_menu, rewrites joined
-- getParentCategories - Category[], only active
-- getChildrenCategories - collection, only active, only immediate, include_in_menu*, rewrites joined
-
-## Describe the category hierarchy tree structure implementation (the internal structure inside the database).
-- Every category has hierarchy fields: parent_id, level, path
-- To avoid recursive parent-child traversing, flat category path is saved for every category. It includes
-  all parents IDs. This allows to optimize children search with single query. E.g. to search children of
-  category id 2 and knowing its path '1/2', we can get children:
-
-  `select * from catalog_category_entity where path like "1/2/%"`:
-
-  ```
-  +-----------+-----------+--------------+-------+
-  | entity_id | parent_id | path         | level |
-  +-----------+-----------+--------------+-------+
-  |         3 |         2 | 1/2/3        |     2 |
-  |         4 |         3 | 1/2/3/4      |     3 |
-  |         5 |         3 | 1/2/3/5      |     3 |
-  |         6 |         3 | 1/2/3/6      |     3 |
-  |         7 |         2 | 1/2/7        |     2 |
-  |         8 |         7 | 1/2/7/8      |     3 |
-  ....
-  ```
-
-
-## What is the meaning of parent_id 0?
-Magento\Catalog\Model\Category constants:
-- ROOT_CATEGORY_ID = 0 -- looks like some reserved functionality, has only one child
-- TREE_ROOT_ID = 1 -- all store group root categories are assigned to this node
-
-- These categories are not visible in admin panel in category management.
-- When creating root category from admin, parent_id is always TREE_ROOT_ID = 1.
-- [Magento\Store\Model\Store::getRootCategoryId](https://github.com/magento/magento2/blob/2.2-develop/app/code/Magento/Store/Model/Store.php#L998):
-  * TREE_ROOT_ID = 1 when store group is not selected
-  * store group root category ID
-- store group root category allows only selecting from categoryes with parnet_id = TREE_ROOT_ID = 1
-
-## How are paths constructed?
-
-Slash-separates parents and own ID.
-
-## Which attribute values are required to display a new category in the store?
-
-- is_active = 1
-- include_in_menu = 1, but even if not displayed in menu, can be opened by direct link
-- url_key can be created automatically based on name
-
-## What kind of strategies can you suggest for organizing products into categories?
diff --git a/7. Customizing the Catalog/4. Determine and manage catalog rules.md b/7. Customizing the Catalog/4. Determine and manage catalog rules.md
deleted file mode 100644
index f98d9b7..0000000
--- a/7. Customizing the Catalog/4. Determine and manage catalog rules.md	
+++ /dev/null
@@ -1,99 +0,0 @@
-# Determine and manage catalog rules
-
-*Primary tables*:
-- `catalogrule` - dates from/to, conditions serialized, actions serialized, simple action, discount amount
-- `catalogrule_website` - rule-website
-- `catalogrule_customer_group` - rule-customer group
-
-*Index tables*:
-- `catalogrule_product` - time from/to, customer group, action operator/amount
-- `catalogrule_product_price` - customer group, rule date, rule price, latest start date, earlier end date
-- `catalogrule_group_website` - rule to customer group, website.
-  Just unique rule/customer group/websites that currently exist in index table `catalogrule_product` for *today*.
-
-*Replica tables* - used to fast switch new index data:
-- `catalogrule_product_replica`
-- `catalogrule_product_price_replica`
-- `catalogrule_group_website_replica`
-
-## Apply rules
-- [*Cron job*](https://github.com/magento/magento2/tree/2.2-develop/app/code/Magento/CatalogRule/Cron/DailyCatalogUpdate.php) 01:00 am invalidates `catalogrule_rule` indexer.
-- Clicking ["Apply rules"](https://github.com/magento/magento2/tree/2.2-develop/app/code/Magento/CatalogRule/Model/Rule/Job.php#L54), ["Save and apply"](https://github.com/magento/magento2/tree/2.2-develop/app/code/Magento/CatalogRule/Controller/Adminhtml/Promo/Catalog/Save.php#L97) in admin panel invalidates indexer as well.
-- Cron job `indexer_reindex_all_invalid`, running every minute, will pick it up and call indexer
-  * Magento\CatalogRule\Model\Indexer\AbstractIndexer::executeFull
-  * [Magento\CatalogRule\Model\Indexer\IndexBuilder::reindexFull](https://github.com/magento/magento2/tree/2.2-develop/app/code/Magento/CatalogRule/Model/Indexer/IndexBuilder.php#L280)
-
-index builder.[doReindexFull](https://github.com/magento/magento2/tree/2.2-develop/app/code/Magento/CatalogRule/Model/Indexer/IndexBuilder.php#L297):
-- clear tables `catalogrule_product`, `catalogrule_product_price`
-- for every rule, reindex rule product.
-  "one day, maybe today, maybe in a year, this rule will match these products"
-
-  * this is regardless of dates, dates are simply written in table for later uage
-  * get matching product IDs
-  * insert into `catalogrule_product` (`_replica`) combinations: product/website/customer group
-- reindex product prices `catalogrule_product_price` (`_replica`).
-  For yesterday, today and tomorrow reads "planned" products, and executes price update
-  starting from initial product.price attribute value. If multiple rules match in same date,
-  they will all apply (unless stop flag).
-
-  * dates = [yesterday; today; tomorrow]
-  * for each website:
-  * read ALL planned products from `catalogrule_product` from all rules, join `price` product attribute
-    + \Magento\CatalogRule\Model\Indexer\RuleProductsSelectBuilder::build
-  * programmatically filter dates (from/to)
-  * calculates price
-    + \Magento\CatalogRule\Model\Indexer\ProductPriceCalculator::calculate
-    + to fixed/to percent/by fixed/by percent
-  * groups by [date, product id, website id, customer group id]
-  * persists to `catalogrule_product_price`
-    + \Magento\CatalogRule\Model\Indexer\RuleProductPricesPersistor::execute
-- reindex *rule relations* with *customer groups and websites* `catalogrule_group_website` (`_replica`)
-  * `catalogrule_group_website` - distinct combinations of customer group and website matched for *today*
-- switches tables from replica to active
-
-## Catalog rule price info
-[Magento\CatalogRule\Pricing\Price\CatalogRulePrice::getValue](https://github.com/magento/magento2/tree/2.2-develop/app/code/Magento/CatalogRule/Pricing/Price/CatalogRulePrice.php#L88)
-- product.data('catalog_rule_price') can be preselected by collection from index.
-  Used only by bundle and is deprecated.
-  * \Magento\CatalogRule\Model\ResourceModel\Product\CollectionProcessor::addPriceData - join catalogrule_product_price
-- [Magento\CatalogRule\Model\ResourceModel\Rule::getRulePrice](https://github.com/magento/magento2/tree/2.2-develop/app/code/Magento/CatalogRule/Model/ResourceModel/Rule.php#L162) by (date, website, customer group, product)
-- rule.getRulePrices
-- loads directly from DB `catalogrule_product_price`
-
-
-## Identify how to implement catalog price rules.
-Matching products - conditions and actions serialized, are implemented on
-foundation of abstract rules [Magento\Rule\Model\AbstractModel](https://github.com/magento/magento2/tree/2.2-develop/app/code/Magento/Rule/Model/AbstractModel.php):
-- conditions - [Magento\Rule\Model\Condition\AbstractCondition](https://github.com/magento/magento2/tree/2.2-develop/app/code/Magento/Rule/Model/Condition/AbstractCondition.php), [combine](https://github.com/magento/magento2/tree/2.2-develop/app/code/Magento/Rule/Model/Condition/Combine.php)
-- actions - [Magento\Rule\Model\Action\AbstractAction](https://github.com/magento/magento2/tree/2.2-develop/app/code/Magento/Rule/Model/Action/AbstractAction.php), collection
-
-Admin form:
-- \Magento\CatalogRule\Block\Adminhtml\Promo\Catalog\Edit\Tab\Conditions
-- conditions renderer \Magento\Rule\Block\Conditions
-- \Magento\Rule\Model\Condition\AbstractCondition::asHtmlRecursive:
-  * TypeElementHtml
-  * AttributeElementHtml
-  * OperatorElementHtml
-  * ValueElementHtml
-  * RemoveLinkHtml
-  * ChooserContainerHtml
-  
-Matching products:
-- [Magento\CatalogRule\Model\Rule::getMatchingProductIds](https://github.com/magento/magento2/tree/2.2-develop/app/code/Magento/CatalogRule/Model/Rule.php#L294)
-- get product collection
-- for each product, run [rule::callbackValidateProduct](https://github.com/magento/magento2/tree/2.2-develop/app/code/Magento/CatalogRule/Model/Rule.php#L329)
-- check if product matches conditions [Magento\Rule\Model\Condition\Combine::validate](https://github.com/magento/magento2/tree/2.2-develop/app/code/Magento/Rule/Model/Condition/Combine.php#L331)
-
-## When would you use catalog price rules?
-- set up discount 30% on Helloween that starts in a month
-- for b2b website, discount 10% from all prices
-- VIP customer group members get 
-
-## How do they impact performance?
-- one SQL query on every final price request
-- reindexing seems not optimized, dates match in PHP and not SQL
-
-## How would you debug problems with catalog price rules?
-- Check indexes `catalogrule_product` - find row by product id, ensure found - rule matched
-- Ensure needed rule matched and unwanted rules didn't match, check sort_order, check from_time and to_time, ensure correct
-- check `catalogrule_product_price` contains product within +-1 day
diff --git a/7.Magento-Customising-The-Catalogue.md b/7.Magento-Customising-The-Catalogue.md
new file mode 100755
index 0000000..5e21f0f
--- /dev/null
+++ b/7.Magento-Customising-The-Catalogue.md
@@ -0,0 +1,1416 @@
+7 - Customising the Catalogue
+==============================
+
+7.1 Demonstrate ability to use products and product types
+---------------------------------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**Identify/describe standard product types (simple, configurable, bundled, etc.).**
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Simple Product
+
+> This is the most basic and the most popular product type. A single simple product corresponds to a single physically existing product to a unique Store Keeping Unit (SKU). A simple product can be sold individually or as part of a [Grouped](#h.fdbtjoju72x), [Configurable](#h.98cgcmsgdbu5), or [Bundle](#h.kvd5wn1qb9e) product.
+>
+> A Simple product MUST have an Attribute Set (or [product template](https://docs.magento.com/user-guide/stores/attribute-sets.html&sa=D&ust=1609223265371000&usg=AOvVaw3KA-UfRdUrjtpunGMSwZiO)) plus ALL required / basic fields filled.
+>
+> A simple product can have custom options with a variety of input controls, which makes it possible to sell many product variations from a single SKU. A simple product with custom options is sometimes referred to as a Composite Product.
+>
+> Example:
+
+![](./images/Magento2-Certification-Exam-Notes-Detailed-Insight-Simple-Product.jpg)
+
+> Required settings include:
+
+1.  SKU
+2.  Price
+3.  Enable Product set to either Yes or No
+
+> Basic setting include:
+
+1.  A Tax Class:
+
+    *  Taxable Goods
+    *  None
+
+2.  Quantity:
+
+    *  Basic
+    *  Multi Source using Inventory Management
+
+3.  Stock Status
+
+    *  In Stock
+    *  Out Of Stock
+
+4.  Weight
+5.  Visibility
+6.  Assign Categories
+7.  Country of Manufacture
+8.  An Assigned Website
+
+> WITHOUT these settings filled, the product MAY NOT appear in the front-end as expected.
+>
+> Other settings:
+
+1.  [Content](https://docs.magento.com/user-guide/catalog/product-content.html&sa=D&ust=1609223265376000&usg=AOvVaw38mJ-fGRy3PdTPGOW6kaR3)
+2.  [Images and Videos](https://docs.magento.com/user-guide/catalog/product-images-and-video.html&sa=D&ust=1609223265377000&usg=AOvVaw0vfkUjOLxY6p73AT_u5DED)
+3.  [Related Products, Up-Sells, and Cross-Sells](https://docs.magento.com/user-guide/catalog/related-products-up-sells-cross-sells.html&sa=D&ust=1609223265378000&usg=AOvVaw01cnypdM3Dn3E0cqKwBskr)
+4.  [Search Engine Optimization](https://docs.magento.com/user-guide/catalog/product-search-engine-optimization.html&sa=D&ust=1609223265378000&usg=AOvVaw0xMt9GiabiofhnRypczou_)
+5.  [Customizable Options](https://docs.magento.com/user-guide/catalog/settings-advanced-custom-options.html&sa=D&ust=1609223265378000&usg=AOvVaw0rdD1DEuqVavWLstDl3kk-)
+6.  [Products in Websites](https://docs.magento.com/user-guide/catalog/settings-basic-websites.html&sa=D&ust=1609223265379000&usg=AOvVaw122LUOO79famVgMIC-iOPx)
+7.  [Design](https://docs.magento.com/user-guide/catalog/settings-advanced-design.html&sa=D&ust=1609223265379000&usg=AOvVaw2IhPmNax9NygwvcA1vHWWz)
+8.  [Gift Options](https://docs.magento.com/user-guide/catalog/product-gift-options.html&sa=D&ust=1609223265380000&usg=AOvVaw1n_x4het5CNGsKmDYQzjBZ)
+
+> [More on how to set up a simple product here](https://docs.magento.com/user-guide/catalog/product-create-simple.html&sa=D&ust=1609223265380000&usg=AOvVaw2HDMJqY8RZk6vF3nn77Dn_).
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Virtual Product
+
+> Virtual products are a product type for the products that do not exist physically. This can represent non-tangible items such as memberships, services, warranties, or subscriptions and digital goods / downloads of books, music, videos, or other products. Virtual products can be sold individually or included as part of the [Grouped Product](#h.fdbtjoju72x) or [Bundle Product](#h.kvd5wn1qb9e) product types.
+>
+> Example:
+
+![](./images/Magento2-Certification-Exam-Notes-Detailed-Insight-Virtual-Product.jpg)
+
+> Aside from the absence of the Weight field, the process of creating a Virtual Product and a [Simple Product](#h.cbgifdse6zd5) are the same.
+>
+> In the front-end workflow, Virtual products skip the shipping step at checkout (seeing as they cannot be fulfilled in that sense) unless there is a tangible product in the cart.
+>
+> [More on how to create a Virtual Product here.](https://docs.magento.com/user-guide/catalog/product-create-virtual.html&sa=D&ust=1609223265383000&usg=AOvVaw0DPQ7FPT0H8xtBHvmZ4UXp)
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Configurable Product
+
+> A Configurable Product looks like a [Simple Product](#h.cbgifdse6zd5) with drop-down lists of options for each variation. Each option is actually a separate [Simple Product](#h.cbgifdse6zd5) with a unique SKU, which makes it possible to track inventory for each variation. These are often called Product Variations or Associated Simple Products. In the context of code, they can be referred to as Sub-Products or Children.
+>
+> You could achieve a similar effect by using a [Simple Product](#h.cbgifdse6zd5) with custom options (Composite Product) but this route loses the ability to track inventory for each variation.
+>
+> Product Variations can appear in the front-end in the form of [Drop-Down](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/select&sa=D&ust=1609223265385000&usg=AOvVaw32rdc-nYgAxQ9GpWsxAGG4), [Multiple Select](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/select&sa=D&ust=1609223265385000&usg=AOvVaw32rdc-nYgAxQ9GpWsxAGG4), [Visual Swatch](https://docs.magento.com/user-guide/catalog/swatches.html&sa=D&ust=1609223265386000&usg=AOvVaw0CXOJxRqWUDa9qnM4enB43) and [Text Swatch](https://docs.magento.com/user-guide/catalog/swatches.html&sa=D&ust=1609223265386000&usg=AOvVaw0CXOJxRqWUDa9qnM4enB43) input types.
+>
+> An example of a Configurable would be a T-shirt in different colors and sizes. Each product option of such configurable products corresponds to a single Simple Product with a unique SKU, allowing the retailer to keep track of each product option stock balance:
+
+![](./images/Magento2-Certification-Exam-Notes-Detailed-Insight-Configurable-Product.jpg)
+
+> The configurable product acts as a sort of umbrella / parent and holds no price or stock information by itself. The associated simple product will be the item that appears in the cart.
+>
+> Creating a Configurable Product follows the same process as with a Simple Product except for an extra step: [Assigning Product Configurations](https://docs.magento.com/user-guide/catalog/product-create-configurable.html%23part-2-adding-configurations&sa=D&ust=1609223265387000&usg=AOvVaw0g4Y29zQG7-4nnj5cKCz13). Each configuration provides the ability to assign independent images, price, and quantity.
+>
+> For price there are 2 methods:
+
+1.  Apply the same price to all SKUs
+2.  Apply a different price for each SKU
+
+> For quantity there are also 2 methods:
+
+1.  Apply the same quantity to all SKUs
+2.  Apply Different Quantity by Attribute
+
+> As is for images, there are 2 methods:
+
+1.  Apply a single set of images to all SKUs
+2.  Apply unique images for each SKU
+
+[More on how to create a Configurable Product here.](https://docs.magento.com/user-guide/catalog/product-create-configurable.html&sa=D&ust=1609223265390000&usg=AOvVaw3tbxvl3QYxCrtluTMJst4T)
+
+![Magento Exam Information](./images/icon-info.png)The attributes that are used for product variations must have a Global Scope and the customer must be required to choose a value. The product variation attributes must be included in the attribute set that is used as a template for the configurable product.
+
+![Magento Exam Information](./images/icon-info.png)The Attribute Set that is used as a template for a configurable product must include the attribute(s) that contain the values that are needed for each product variation.
+
+![Magento Exam Information](./images/icon-info.png)The thumbnail image in the shopping cart can be set to display the image from the configurable product record or from the product variation.
+
+![Magento Exam Information](./images/icon-info.png)Configurable Products DO NOT have prices.
+
+![Magento Exam Information](./images/icon-info.png)Configurable Products DO NOT have stock information.
+
+![Magento Exam Information](./images/icon-info.png)Configurable Products DO NOT NEED weights.
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Grouped Product
+
+> A grouped product consists of simple standalone products that are presented as a group. You can offer variations of a single product or group them by season or theme.
+>
+> Presenting a grouped product can create an incentive for customers to purchase additional items. A grouped product provides an easy way to offer variations of a product and list them all on the same page. This product type allows the grouping of single [Simple](#h.cbgifdse6zd5) or [Virtual](#h.t3fkw0wf3trp) Products into collections. Moreover, the customer gets to decide which products from the collection she/he wants to purchase and in what amount.
+>
+> ![](./images/Magento2-Certification-Exam-Notes-Detailed-Insight-Grouped-Products.jpg)
+>
+> Although they are presented as a group, each product in the group is purchased as a separate item. In the shopping cart, each item and the quantity purchased appears a separate line item.
+>
+> Aside from the extra step of [Adding Products to a Group within the Grouped Products section](https://docs.magento.com/user-guide/catalog/product-create-grouped.html%23step-5-add-products-to-the-group&sa=D&ust=1609223265392000&usg=AOvVaw1N6ZzJozW59FKwdXbcyIDI), the process of creating a Grouped Product and a Simple Product are the same.
+>
+> [More on how to create a Grouped Product here.](https://docs.magento.com/user-guide/catalog/product-create-grouped.html&sa=D&ust=1609223265393000&usg=AOvVaw3_D0y2sK9-SS2GvAgfyx6f)
+
+
+![Magento Exam Information](./images/icon-info.png)A grouped product is essentially a collection of simple associated products.
+
+![Magento Exam Information](./images/icon-info.png)Each item purchased appears individually in the shopping cart, rather than as part of the group.
+
+![Magento Exam Information](./images/icon-info.png)The thumbnail image in the shopping cart can be set to display the image from the grouped parent product or associated product.
+
+![Magento Exam Information](./images/icon-info.png)Grouped Products DO NOT have prices.
+
+![Magento Exam Information](./images/icon-info.png)Grouped Products DO NOT have stock information.
+
+![Magento Exam Information](./images/icon-info.png)Grouped Products DO NOT NEED weights.
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Bundle Product
+
+> A bundle is a build your own, customizable product. Each item in a bundle can be based on one of the following product types:
+>
+> *   [Simple Product](#h.cbgifdse6zd5)
+> *   [Virtual Product](#h.t3fkw0wf3trp)
+>
+> The options in the front-end appear when the customer clicks either Customize or Add to Cart. This is because the products that are included in the bundle vary. A SKU, Price, or Weight can be set to either a dynamic or fixed value. An exception would be unless [Instant Purchase](https://docs.magento.com/user-guide/sales/checkout-instant-purchase.html&sa=D&ust=1609223265396000&usg=AOvVaw2phbhJSDX7LwzFeTI6MAp0) is available.
+>
+> Add 1 composite product, consisting of many selected variations, options independent. SKU dynamic/fixed, weight dynamic/fixed, price dynamic/fixed. Each qty x total qty.
+>
+>
+> Ror example, a yoga kit:
+![](./images/Magento2-Certification-Exam-Notes-Detailed-Insight-Bundle-Product.jpg)
+
+
+> Each option is a [Simple Product](#h.cbgifdse6zd5) or a [Virtual Product](#h.t3fkw0wf3trp). Before adding a bundle product to the cart, a customer must customize it with the provided options. The final price will depend on the chosen configuration.
+>
+> ![](./images/Magento2-Certification-Exam-Notes-Detailed-Insight-Bundle-Product-Options.jpg)
+>
+> SKU and Weight attributes can be fixed or dynamic. The price for Bundle Product can be set as Price Range (from minimum to maximum) or As Low As (the lowest price possible). The admin can set how the products will be delivered – together or separately.
+>
+> Inventory is tracked separately for each child.
+>
+> Aside from the extra step of [Adding Bundle Items within the Bundle Items section](https://docs.magento.com/user-guide/catalog/product-create-bundle.html%23step-5-add-the-bundle-items&sa=D&ust=1609223265398000&usg=AOvVaw00U83xfQoeYOrkYTQMqnz1), the process of creating a Bundle Product and a [Simple Product](#h.cbgifdse6zd5) are the same.
+>
+> The SKU of bundle items can be set as either Dynamic or Fixed. If you set SKU as Dynamic, each bundle item SKU is assigned by adding a suffix to the default SKU. If you set SKU as fixed, you can assign a unique SKU for each bundle item.
+>
+> With bundle product weight, a Fixed weight setting allows you to set a determined value for bundle products directly, but with Dynamic weight, you can not set a weight value to bundle products. Instead, the weight of the bundle is calculated from the selected bundle items.
+>
+> If you set a Fixed price for a bundle product, you can enter a base price with applied taxes for it. For Dynamic price setting, the bundle price and tax class attribute are disabled, and the price of the bundle is composed of the item prices in options. Moreover, you can set the price viewing on the category page and the product details page in case you set a Magento bundle product price is Dynamic. If you select Price Range, the lowest and the highest prices calculated from option item prices will be displayed. If you set it to As Low As, the lowest possible price of the bundle will be shown only. Of course, the final price depends on the price of products that are selected by purchasers.
+
+
+![Magento Exam Information](./images/icon-info.png)How I remember this is that it's a configurable [Grouped Product](#h.pedurdgu5za5). Customers can build their own bundle product.
+
+![Magento Exam Information](./images/icon-info.png)Bundle items can be simple or virtual products without custom options.
+
+![Magento Exam Information](./images/icon-info.png)The Price View can be set to either Price Range or As Low As.
+
+![Magento Exam Information](./images/icon-info.png)SKU and Weight can be either Fixed or Dynamic by adding a suffix to the default value. By default, this is set to Yes.
+
+![Magento Exam Information](./images/icon-info.png)The quantity can be a preset or user-defined value. However, do not assign the User Defined property to checkbox or multiple-select input types.
+
+![Magento Exam Information](./images/icon-info.png)Bundle items can be shipped together or separately.
+
+![Magento Exam Information](./images/icon-info.png)A Minimum Advertised Price (MAP) is not available for Bundle products that use dynamic pricing.
+
+![Magento Exam Information](./images/icon-info.png)The Instant Purchase button appears below the Add to Cart button for each item in the bundle. When enabled, the Instant Purchase button appears below the Add to Cart button on the product page for customers who [meet the requirements](https://docs.magento.com/user-guide/sales/checkout-instant-purchase.html%23customer-requirements&sa=D&ust=1609223265401000&usg=AOvVaw1SxKAe89rZ1LC1_8M1Hr8w).
+
+![Magento Exam Information](./images/icon-info.png)Bundle Products DO NOT have prices.
+
+![Magento Exam Information](./images/icon-info.png)Bundle Products DO NOT have stock information.
+
+![Magento Exam Information](./images/icon-info.png)Bundle Products DO NOT have weights.
+
+![Magento Exam Information](./images/icon-info.png)Bundle Products DO NOT have tax information
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Downloadable Product
+
+> A Downloadable Product can be anything that you can deliver as a file, such as an eBook, music, video, software application, or update. You can offer an album for sale and sell each song individually. You can also use a downloadable product to deliver an electronic version of your product catalog.
+>
+> Downloadable Products can consist of one or several files. Because the actual download is not available until after the purchase, you can provide samples, such as an excerpt from a book, a clip from an audio file, or a trailer from a video that the customer can try before purchasing the product. The files that you make available for download can be either uploaded to your server or from a different server.
+>
+> Example:
+
+![](./images/Magento2-Certification-Exam-Notes-Detailed-Insight-Downloadable-Product.jpg)
+
+> Downloadable products can be configured to require that the customer log in to an account to receive the link OR they can be sent by email and shared with others.
+>
+> The status of the order before the download becomes available, default values, and other delivery options are set in the configuration. Fore more information, see Download Options.
+>
+> Aside from the extra step of [Configuring the Format](https://docs.magento.com/user-guide/catalog/product-create-downloadable.html%23step-4-complete-the-basic-settings&sa=D&ust=1609223265404000&usg=AOvVaw0YMZFDqLkiVrIFKiJn5zmR) & [Downloadable Information](https://docs.magento.com/user-guide/catalog/product-create-downloadable.html%23step-5-complete-the-downloadable-information&sa=D&ust=1609223265405000&usg=AOvVaw2xRf-bKDgLDjPu8me25pj1), the process of creating a Downloadable Product and a [Simple Product](#h.cbgifdse6zd5) are the same. The [Downloadable Configuration Settings](https://docs.magento.com/user-guide/catalog/product-download-options.html&sa=D&ust=1609223265405000&usg=AOvVaw2pNtAXRJs8EqHdvJb9UOQh) determine the default values and delivery options for downloadable products and specify if guests can purchase downloads.
+
+[More on how to create Downloadable Products here.](https://docs.magento.com/user-guide/catalog/product-create-downloadable.html&sa=D&ust=1609223265406000&usg=AOvVaw1JxvkhMtbwT9kGC-8W0Dcw)
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Gift Card Product (Commerce / Enterprise edition)
+
+> There are three kinds of gift card products:
+>
+> **Virtual**
+>
+> A virtual gift card is sent to the recipient's email address, which is required during the purchase of the gift card. A shipping address is not necessary (similar front-end interface as [Virtual Products](#h.t3fkw0wf3trp)).
+>
+> **Physical**
+>
+> A physical gift card is shipped to the recipient's address, which is required during the purchase of the gift card (similar front-end interface as [Simple Products](#h.cbgifdse6zd5)).
+>
+> **Combined**
+>
+> A combined gift card is shipped and emailed to the recipient. The recipient's email and shipping address is required during the purchase of the gift card (similar front-end interface as Physical).
+>
+> Example:
+
+![](./images/Magento2-Certification-Exam-Notes-Detailed-Insight-Giftcard-Product.png)
+
+> Gift cards are redeemed in the shopping cart similar to the way a coupon is applied to an order. During checkout, the shopper enters the gift card code to apply an amount from the gift card to the purchase. Gift card holders who have customer accounts can check the status and remaining balance from their account dashboard. Single, as well as multiple, gift cards can be used to pay for all or part of an order. It can be redeemed on any store / website and will never expire.
+>
+> Gift Card Workflow:
+
+1.  Customer determines the gift card value
+2.  Customer completes the gift card information
+3.  Customer completes checkout
+4.  Customer receives confirmation of the order
+5.  Recipient receives the gift card
+6.  Recipient applies gift card to purchase
+
+![Magento Exam Information](./images/icon-info.png)Gift Cards are only available in Commerce / Enterprise edition.
+
+![Magento Exam Information](./images/icon-info.png)If a gift card order is canceled or refunded, you must manually cancel the associated gift card account. You can either delete the account entirely or deactivate it via Admin.
+
+![Magento Exam Question](./images/icon-question.png)**How would you obtain a product of a specific type?**
+
+Using `Magento\Catalog\Model\ResourceModel\Product\Collection` like so:
+
+```php
+$productCollection->addFieldToFilter('type_id', 'simple');
+```
+
+![Magento Exam Information](./images/icon-info.png)Using the `Magento\Catalog\Api\ProductRepositoryInterface` doesn't work here because currently `Magento\Framework\Api\SearchCriteriaInterface` doesn't have the ability to select specific fields.
+
+![Magento Exam Question](./images/icon-question.png)**What tools (in general) does a product type model provide?**
+
+> All general product type methods are available (public) in `Magento\Catalog\Model\Product`:
+
+*   `getId`/`setId` - Getter & setter of entity_id (try avoiding setting IDs however).
+*   `getStoreId`/setStoreId - Setting the store view ID this product belongs to.
+*   `getWebsiteIds` - Setting the website ID this product belongs to.
+*   `getStoreIds` - Get store IDs as arrays in case there are many.
+*   `getUrlModel`/`getLinkInstance` - Return `Magento\Catalog\Model\Product\Url` instance for this product.
+*   `validate` - Validate Product Data.
+*   `getName`/`setName` - Getter & setter of product name.
+*   `getVisibility`/`setVisibility` - Getter & setter of products visibility in catalog + search (@param int).
+*   `getSku`/`setSku` - Getter & setter of products stock-keeping unit.
+*   `getAttributeSetId`/`setAttributeSetId` - Getter & setter of the Attribute Set or product template.
+*   `getCreatedAt`/`setCreatedAt` - Getter & setter of the products first created date - this is automatic when saving products.
+*   `getUpdatedAt`/`setUpdatedAt` - Getter & setter of when this product was last updated - this is automatic when saving products.
+*   `getTypeId`/`setTypeId` - Getter & setter of the products type (@param int)
+*   `getStatus`/`setStatus` - Getter & setter of stock status of this product (in stock / out of stock).
+*   `getWeight`/`setWeight` - Getter & setter of products weight.
+*   `getTypeInstance`/setTypeInstance - Getter & setter of type instance `Magento\Catalog\Model\Product\Type\AbstractType`. Type instance implements product type dependent logic and is a singleton shared by all products of the same type.
+*   `getIdBySku` - return entity_id of this product by SKU.
+*   `getCategoryId` - Get the current category of this product.
+*   `getCategory` - Get the current category of this product as `Magento\Catalog\Model\Category`
+*   `getCategoryIds` - Get all categories belonging to this product as array
+*   `getCategoryCollection` - Get the current category of this product as `Magento\Framework\Data\Collection` (Setter is protected).
+*   `getStockData`/setStockData - Getter & setter of StockItemInterface data as array
+*   `getAttributes` - Retrieve product attributes as an array of `Magento\Eav\Model\Entity\Attribute\AbstractAttribute`.
+*   `beforeSave` - Check product options and type options and save them, too.
+*   `canAffectOptions` - Check/set if options can be affected when saving products. If the value is specified, it will be set.
+*   `afterSave` - Saving product type related data and init index.
+*   `getQty`/`setQty` - Getter & setter of product quantity.
+*   `priceReindexCallback` - Callback for reindex specific to this entity.
+*   `eavReindexCallback` - Reindex callback for EAV indexers.
+*   `isDataChanged` - Check if data was changed.
+*   `reindex` - Init indexing process after product save.
+*   `beforeDelete` - Clear cache related to product and protect delete from not admin.
+*   `afterDeleteCommit` - Init indexing process after product delete commit.
+*   `cleanCache` - Clean (not clear) cache related with product id.
+*   `getPrice`/`setPrice` - Getter & setter of products price.
+*   `setPriceCalculation` - Set Price calculation flag
+*   `getPriceModel` - Get price model `Magento\Catalog\Model\Product\Type\Price` based on product type.
+*   `getPriceInfo` - Return base price information as `Magento\Framework\Pricing\PriceInfo\Base`
+*   `getTierPrices`/setTierPrices - Getter & setter list of product tier prices as `Magento\Catalog\Api\Data\ProductTierPriceInterface`
+*   `getTierPrice` - Get product tier price for the customer, based on qty of this product as float
+*   `getFormatedPrice`/getFormattedPrice - Get formatted by currency product price
+*   `getFinalPrice` - Get products price including tax and discount.
+*   `setFinalPrice` - Accepts a $price parameter but, this func is equal to magic 'setFinalPrice()', but added as a separate func, because in cart with bundle products it's called very often in Item->getProduct(). So removing the chain of magic with more cpu consuming algorithms gives a nice optimization boost.
+*   `getCalculatedFinalPrice` - Returns calculated final price.
+*   `getMinimalPrice` - Returns most minimal price of product.
+*   `getSpecialPrice` - Get sales price of product.
+*   `getSpecialFromDate` - Returns starting date of the special price.
+*   `getSpecialToDate` - Returns ending date of the special price.
+*   `getRelatedProducts` - Get related product `Magento\Catalog\Model\Product` as array.
+*   `getRelatedProductIds` - Get related product IDs.
+*   `getRelatedProductCollection` - Retrieve collection related products as `Magento\Catalog\Model\ResourceModel\Product\Link\Product\Collection`.
+*   `getRelatedLinkCollection` - Retrieve link collections related to the object `Magento\Catalog\Model\ResourceModel\Product\Link\Collection`.
+*   `getUpSellProducts` - Get up-sell product `Magento\Catalog\Model\Product` as array.
+*   `getUpSellProductIds` - Get up-sell product IDs.
+*   `getUpSellProductCollection` - Retrieve collection up-sell product as `Magento\Catalog\Model\ResourceModel\Product\Link\Product\Collection`.
+*   `getUpSellLinkCollection` - Retrieve link collections of up-sell as `Magento\Catalog\Model\ResourceModel\Product\Link\Collection`.
+*   `getCrossSellProducts` - Get cross-sell product `Magento\Catalog\Model\Product` as array.
+*   `getCrossSellProductIds` - Get cross-sell product IDs.
+*   `getCrossSellProductCollection` - Retrieve collection cross-sell product as `Magento\Catalog\Model\ResourceModel\Product\Link\Product\Collection`.
+*   `getCrossSellLinkCollection` - Retrieve link collections of cross-sell as `Magento\Catalog\Model\ResourceModel\Product\Link\Collection`.
+*   `getProductLinks`/`setProductLinks` - Getter & setter of product links info as `Magento\Catalog\Api\Data\ProductLinkInterface`.
+*   `getMediaAttributes` - Retrieve attributes for media gallery.
+*   `getMediaAttributeValues` - Retrieve assoc array that contains media attribute values of the product.
+*   `getMediaGalleryImages` - Retrieve media gallery images as `Magento\Framework\Data\Collection`.
+*   `hasGalleryAttribute` - Checks whether a product has a Media Gallery attribute.
+*   `addImageToMediaGallery` - Add image to media gallery (@param string $file)
+*   `getMediaConfig` - Retrieve product media config
+*   `getVisibleInCatalogStatuses` - Returns visible status IDs in catalog
+*   `getVisibleStatuses` - Retrieve visible statuses
+*   `isVisibleInCatalog` - Check Product visible in catalog
+*   `getVisibleInSiteVisibilities` - Retrieve visible in site visibilities
+*   `isVisibleInSiteVisibility` - Check Product visible in site
+*   `isDuplicable`/setIsDuplicable - Getter & setter of checks for whether a product has been duplicated
+*   `isSalable`/isSaleable - Check is product available for sale. Product needs to be enabled, Configurables & bundles need to have at least one salable simple product. Downloadables need to have at least one link.
+*   `isAvailable` - Check whether the product type or stock allows you to purchase the product. It only checks isSalable on that specific product type.
+*   `getIsSalable` - Is product salable detecting by product type.
+*   `isVirtual`/getIsVirtual - Check if this product is virtual.
+*   `isInStock` - Check the stock status is in stock.
+*   `getAttributeText` - Get an attribute value by its code (`@param string $attributeCode`).
+*   `getCustomDesignDate` - Returns array with dates for custom design.
+*   `getProductUrl` - Retrieve Product URL.
+*   `getUrlInStore` - Retrieve URL in current store.
+*   `formatUrlKey` - Formats URL key.
+*   `addAttributeUpdate` - Save current attribute with code $code and assign new value (@param string $code).
+*   `toArray` - Get product data as an array.
+*   `fromArray` - Same as setData(), but also initiates the stock item (if it is there).
+*   `getRequestPath` - Returns request path.
+*   `getGiftMessageAvailable` - Custom function for other modules, gift messages for product.
+*   `isComposite` - Is this a [Composite Product](#h.cbgifdse6zd5) (product with custom options).
+*   `canConfigure` - Check if product options can be configured.
+*   `getOptionInstance` - Get product options as `Magento\Catalog\Model\Product\Option`.
+*   `addOption` - Add option to array of product options (@param `Magento\Catalog\Model\Product\Option`).
+*   `getOptionById` - Get option from options array of product by given option id.
+*   `getProductOptionsCollection` - Retrieve product options collection as `Magento\Catalog\Model\ResourceModel\Product\Option\Collection`.
+*   `getOptions`/setOptions - Getter & setter of product options (@param `Magento\Catalog\Api\Data\ProductCustomOptionInterface`).
+*   `addCustomOption`/getCustomOption - Getter & setter of a custom option information to product (@param string $code, @param string value).
+*   `getCustomOptions`/setCustomOptions - Getter & setter of multiple custom options information to product as array.
+*   `hasCustomOptions` - Does this product have custom options
+*   `canBeShowInCategory` - Check availability display of product within category.
+*   `getAvailableInCategories` - Retrieve category IDs where product is available.
+*   `getDefaultAttributeSetId` - Retrieve the default attribute set ID
+*   `reset` - Reset all model data.
+*   `getCacheIdTags` - Get cache tags associated with object ID.
+*   `isProductsHasSku` - Check for empty SKU on each product.
+*   `processBuyRequest` - Parse buyRequest into options values used by the product.
+*   `getPreconfiguredValues` - Get pre configured values from product.
+*   `prepareCustomOptions` - Prepare product custom options. To be sure that all product custom options do not have IDs and have product instances.
+*   `getProductEntitiesInfo` - Retrieve product entities info as array.
+*   `isDisabled` - Checks whether a product has disabled status.
+*   `getImage` - Gets product images from it's child if possible.
+*   `getIdentities` - Get identities.
+*   `reloadPriceInfo` - Refresh the PriceInfo Object.
+*   `toFlatArray` - Convert Category model into flat array
+*   `getExtensionAttributes`/setExtensionAttributes - Getter & setter of [Extension Attributes](#h.aqe3c923mrz4) as `Magento\Framework\Api\ExtensionAttributesInterface`
+*   `getMediaGalleryEntries`/setMediaGalleryEntries - Getter & setter of Media Gallery Entities as `Magento\Catalog\Api\Data\ProductAttributeMediaGalleryEntryInterface`
+*   `setAssociatedProductIds` - Get Configurable Product Super Links / Associated Simple Products (If product is child of configurable).
+*   `getQuantityAndStockStatus`/`setQuantityAndStockStatus` - Getter & setter of quantity and stock status data.
+
+> The following methods are deprecated:
+
+*   `getStockData`/`setStockData` @deprecated 102.0.0.
+*   `getQuantityAndStockStatus`/`setQuantityAndStockStatus` @deprecated 102.0.0 - Product model shouldn't be responsible for stock status.
+*   `setPriceCalculation` @deprecated 102.0.4
+*   `getFormatedPrice` @deprecated 102.0.6
+*   `getCacheIdTags` @deprecated 102.0.5
+
+![Magento Exam Information](./images/icon-info.png)Not expected to memorise a whole class. The most important thing to remember here is that this model allows you to:
+
+*   Set [Basic / Required Information](#h.cbgifdse6zd5) such as you can within admin.
+*   Getting/Setting [Related/Cross-Sell/Up-Sell Products](https://docs.magento.com/user-guide/catalog/related-products-up-sells-cross-sells.html&sa=D&ust=1609223265437000&usg=AOvVaw080lS390-fwBk0-e8Gk6rV).
+*   Checking if this specific product this an [Associated Simple Product](#h.98cgcmsgdbu5).
+*   Getting/Setting/Refreshing Prices, [Group Prices](https://docs.magento.com/user-guide/catalog/product-price-group.html&sa=D&ust=1609223265438000&usg=AOvVaw3RyTK40CFEXIsytwIE6oah), [Tier Prices](https://docs.magento.com/user-guide/catalog/product-price-tier.html&sa=D&ust=1609223265438000&usg=AOvVaw2-vKAcFNdlJX9NU34yG4zY), [Advanced Prices](https://docs.magento.com/user-guide/catalog/pricing-advanced.html&sa=D&ust=1609223265439000&usg=AOvVaw30rg72uQrYlqfLtotvY1b4), [Special Prices](https://docs.magento.com/user-guide/catalog/product-price-special.html&sa=D&ust=1609223265439000&usg=AOvVaw3kGlW9LeG73cLJzojGJ6r_), [Catalog Price Rules](https://docs.magento.com/user-guide/marketing/price-rules-catalog.html&sa=D&ust=1609223265439000&usg=AOvVaw0MwLoDaKG1EbxBZ5mtZpPL) as final, before or after discount/tax, as a Price Object.
+*   Getting/Setting Media Gallery Objects.
+*   Checking if this specific product is salable/available for purchase both configuratively and categorically within scope.
+*   Checking if this specific product is a duplicate.
+*   Getting/Setting [Composite Product](#h.cbgifdse6zd5) Configurations.
+*   Invalidating Cache / Index for this specific product.
+*   Getting product information in desired formats such as an array.
+
+![Magento Exam Question](./images/icon-question.png)**What additional functionality is available for each of the different product types?**
+
+![Magento Section Chevron](./images/icon-chevron.png) Simple (`Magento\Catalog\Model\Product\Type\Simple`):
+
+> Extends `Magento\Catalog\Model\Product\Type\AbstractType` to provide the methods:
+
+*   `prepareForCart` - Initialize product(s) for add to cart process
+*   `checkProductBuyState` - Check if product can be bought
+*   `getOrderOptions` - Prepare additional options/information for the order item which will be created from this product.
+*   `save` - Save type related data ONLY.
+*   `getOptionSku` - Default action to get sku of product with option.
+*   `hasWeight` - defaults to true as this is a tangible product type.
+*   `hasOptions` - Return true if the product has custom options.
+*   `updateQtyOption` - Method is needed for specific actions to change given configuration options values according to current product type logic. Example: the cataloginventory validation of decimal qty can change qty to int, so need to change configuration item qty option value too.
+*   `hasRequiredOptions` - Check if composite product has required custom options
+*   `getStoreFilter`/setStoreFilter - Getter & Setter of store filter for associated products.
+*   `prepareQuoteItemQty` - Prepare Quote Item Quantity
+*   `assignProductToOption` - Implementation of product specify logic of which product needs to be assigned to which option. For example: if a product which was added to option already removed from catalog.
+*   `setConfig` - Sets specific composite product type variables if this is a composite product.
+*   `getSearchableData` - Retrieve additional searchable data from type instance. Using based on product id and store_id data.
+*   `getProductsToPurchaseByReqGroups` - Retrieve products divided into groups required to purchase At least one product in each group has to be purchased
+
+![Magento Section Chevron](./images/icon-chevron.png) Configurable (`Magento\ConfigurableProduct\Model\Product\Type\Configurable`):
+
+Extends `Magento\Catalog\Model\Product\Type\AbstractType` to provide the following additional methods:
+
+*   `getConfigurableAttributes` - Gets the attributes, used for sub-products. Retrieve configurable attributes data.
+*   `getUsedProducts` - Retrieve used associative product as array of `Magento\Catalog\Model\Product`.
+*   `getSalableUsedProducts` - Retrieve only salable used associative product as array of `Magento\Catalog\Model\Product`.
+*   `getUsedProductIds` - Retrieve identifiers of used associative product attributes.
+*   `getUsedProductCollection` - Retrieve ids of associative product attributes as: `Magento\ConfigurableProduct\Model\ResourceModel\Product\Type\Configurable\Product\Collection`
+*   `getChildrenIds` - Retrieve required associative product ids as grouped array
+*   `getParentIdsByChild` - Retrieve parent ids array by required child
+*   `canUseAttribute` - Check attribute availability for super product creation
+*   `getUsedProductAttributeIds`/`setUsedProductAttributeIds` - Getter & setter of attribute identifiers used for assigning associative subproducts
+*   `getProductByAttributes` - Gets associative products by their attribute values.
+*   `getUsedProductAttributes`/`setUsedProductAttributes` - Getter & setter of the list of used attributes to product.
+*   `getSelectedAttributesInfo` - Retrieve the selected Attribute info
+*   `getConfigurableOptions` - Gets options list;
+*   `setImageFromChildProduct` - Sets the image of a child product for a parent product, if it was not set previously.
+*   `getRelationInfo` - Return relation info about used products
+*   `isPossibleBuyFromList` - Checks if all attributes are visible in product listing.
+*   `resetConfigurableAttributes` - Reset the cached configurable attributes of a product
+*   `getConfigurableAttributesAsArray` - Retrieve Configurable Attributes as array
+*   `getConfigurableAttributeCollection` - Retrieve configurable attribute collection object `Magento\ConfigurableProduct\Model\ResourceModel\Product\Type\Configurable\Attribute\Collection`
+*   `isSalable`/`getIsSalable` - Additional checks to ensure all Associated Simple Products are also salable.
+*   `checkProductBuyState` - Check if a product can be bought including Associated Simple Products Attributes.
+*   `getSpecifyOptionMessage` - Retrieve message for specified option(s).
+*   `getOrderOptions` - Prepare additional options/information for the order item which will be created from this product.
+*   `isVirtual` - Should be false, being configurable and all.
+*   `hasOptions` - Check to see if this configurable is also a Composite Product.
+*   `getWeight` - Configurable products themselves do not need a weight. Get the simple product weight, else return value on configurable.
+*   `getProductsToPurchaseByReqGroups` - Retrieve products divided into groups required to purchase. At least one product in each group has to be purchased
+*   `processBuyRequest` - Prepare selected options for configurable product
+*   `getConfigurableOptions` - Prepare and retrieve options values with product data
+*   `deleteTypeSpecificData` - Delete data specific for Configurable product type
+*   `getAttributeById` - Retrieve product attribute by identifier. Difference from abstract: any attribute is available, not just the ones from $product's attribute set
+*   `setImageFromChildProduct` - Set image for product without an image (if possible).
+
+Deprecated:
+
+*   `getUsedProductIds` - @deprecated 100.1.1
+*   `getSalableUsedProducts` - @deprecated 100.2.0 Not used anymore. Keep it for backward compatibility.
+*   `setUsedProductAttributeIds` - @deprecated 100.1.0 use `Magento\ConfigurableProduct\Model\Product\Type\Configurable::setUsedProductAttributes` instead
+
+![Magento Exam Information](./images/icon-info.png)Not expected to memorise a whole class. The most important thing to remember here is that Configurable Products extend General Tools (above) to provide:
+
+*   Access to [Associated Simple Products](#h.98cgcmsgdbu5) as an array from parent.
+*   Refine isSalable to ensure all Associated Simple Products are also Available.
+*   Configurable Products DO NOT have prices.
+*   Configurable Products DO NOT have stock information.
+*   Configurable Products DO NOT NEED weights.
+
+![Magento Section Chevron](./images/icon-chevron.png) Bundle (`Magento\Bundle\Model\Product\Type`):
+
+> Extends `Magento\Catalog\Model\Product\Type\AbstractType` to provide the following additional methods:
+
+*   `getRelationInfo` - Return relation info about used products as object `Magento\Framework\DataObject`
+*   `getChildrenIds` - Retrieve Required children ids. Returns a grouped array, example: [group => [ids]]
+*   `getParentIdsByChild` - Retrieve parent ids array by required child.
+*   `getSku` - Return product sku based on sku_type attribute.
+*   `getWeight` - Return product weight based on weight_type attribute.
+*   `isVirtual` - Check is virtual product within bundle. Defaults to false, being a Bundle.
+*   `getOptions` - Retrieve bundle options items as object `Magento\Framework\DataObject`.
+*   `getOptionsIds` - Retrieve bundle options IDs as array.
+*   `getOptionsCollection` - Retrieve bundle option collection as object `Magento\Bundle\Model\ResourceModel\Option\Collection`.
+*   `getSelectionsCollection` - Retrieve bundle selections collection based on used options as object `Magento\Bundle\Model\ResourceModel\Selection\Collection`.
+*   `updateQtyOption` - Method is needed for specific actions to change given quote options values according current product type logic Example: the catalog inventory validation of decimal qty can change qty to int, so need to change quote item qty option value too.
+*   `prepareQuoteItemQty` - Prepare Quote Item Quantity.
+*   `isSalable` - Checking if we can sale this bundle, all items in bundle need to be salable also.
+*   `getSpecifyOptionMessage` - Retrieve message for specify option(s).
+*   `getSelectionsByIds` - Retrieve bundle selections collection based on ids.
+*   `getOptionsByIds` - Retrieve bundle options collection based on ids as object `Magento\Bundle\Model\ResourceModel\Option\Collection`.
+*   `getOrderOptions` - Prepare additional options/information for order item which will be created from this product.
+*   `shakeSelections` - Sort selections method for usort function. Sort selections by option position, selection position and selection id.
+*   `hasOptions` - Return true if product has options.
+*   `getForceChildItemQtyChanges` - Allow for updates of children qty's.
+*   `getSearchableData` - Retrieve additional searchable data from type instance, Using based on product id and store_id data.
+*   `checkProductBuyState` - Check if product can be bought.
+*   `getProductsToPurchaseByReqGroups` - Retrieve products divided into groups required to purchase. At least one product in each group has to be purchased.
+*   `processBuyRequest` - Prepare selected options for bundle product.
+*   `canConfigure` - Check if product can be configured.
+*   `deleteTypeSpecificData` - Delete data specific for Bundle product type.
+*   `getIdentities` - Return array of specific to type product entities.
+
+![Magento Exam Information](./images/icon-info.png)Not expected to memorise a whole class. The most important thing to remember here is that Bundle Products extend General Tools (above) to provide:
+
+*   Give additional functionality around Getting/Setting Bundle options.
+*   Refine isSalable to ensure all products Bundle Options are also saleable.
+*   Bundle Products DO NOT have prices.
+*   Bundle Products DO NOT have stock information.
+*   Bundle Products DO NOT have weights.
+*   Bundle Products DO NOT have tax information
+
+![Magento Section Chevron](./images/icon-chevron.png)Grouped (`Magento\GroupedProduct\Model\Product\Type\Grouped`):
+
+Extends `Magento\Catalog\Model\Product\Type\AbstractType` to provide the following additional methods:
+
+*   `getRelationInfo` - Return relation info about used products.
+*   `getChildrenIds` - Retrieve Required children ids. Returns a grouped array, example: [group => [ids]].
+*   `getParentIdsByChild` - Retrieve parent ids array by required child.
+*   `getAssociatedProducts` - Retrieve array of associated products as object `Magento\Catalog\Model\Product`.
+*   `flushAssociatedProductsCache` - Flush Associated Products Cache.
+*   `addStatusFilter` - Add status filter to collection (@param  int $status).
+*   `setSaleableStatus` - Set only saleable filter of product (@param  `Magento\Catalog\Model\Product` $product).
+*   `getStatusFilters` - Return all assigned status filters (@param `Magento\Catalog\Model\Product` $product).
+*   `getAssociatedProductIds` - getAssociatedProductIds (@param `Magento\Catalog\Model\Product` $product).
+*   `getAssociatedProductCollection` - Retrieve collection of associated products as object `Magento\Catalog\Model\ResourceModel\Product\Link\Product\Collection` (@param `Magento\Catalog\Model\Product` $product).
+*   `getProductsToPurchaseByReqGroups` - Retrieve products divided into groups required to purchase. At least one product in each group has to be purchased (@param `Magento\Catalog\Model\Product` $product)
+*   `processBuyRequest` - Prepare selected qty for grouped product's options (@param `Magento\Catalog\Model\Product` $product, @param `Magento\Framework\DataObject` $buyRequest). Returns an array.
+*   `hasWeight` - Grouped products do not have any weight.
+*   `deleteTypeSpecificData` - Does nothing
+*   `getChildrenMsrp` - Returns Manufacturer's Suggested Retail Price for children products. Returns int (should be float).
+
+![Magento Exam Information](./images/icon-info.png)Not expected to memorise a whole class. The most important thing to remember here is that Grouped Products extend General Tools (above) to provide:
+
+*   Give additional functionality around Getting/Setting Associated Products..
+*   Refine isSalable to ensure all Associated Products are also saleable.
+*   Grouped Products DO NOT have prices.
+*   Grouped Products DO NOT have stock information.
+*   Grouped Products DO NOT NEED weights.
+
+![Magento Section Chevron](./images/icon-chevron.png) Virtual (`Magento\Catalog\Model\Product\Type\Virtual`):
+
+> Extends Magento\Catalog\Model\Product\Type\AbstractType to provide the following additional methods:
+
+*   `isVirtual` - Returns true.
+*   `hasWeight` - Returns false.
+*   `deleteTypeSpecificData` - Does nothing.
+
+![Magento Exam Information](./images/icon-info.png)Virtual Products skip the shipping step at checkout, being virtual.
+
+![Magento Section Chevron](./images/icon-chevron.png) Downloadable (`Magento\Downloadable\Model\Product\Type`):
+
+Actually extends `Magento\Catalog\Model\Product\Type\Virtual` (above) and adds the following methods:
+
+*   `getLinks` - Get downloadable product links as array Magento\Downloadable\Model\Link[].
+*   `hasLinks` - Check if product has links.
+*   `hasOptions` - Check if product has options.
+*   `hasRequiredOptions` - Check if product has required options.
+*   `getLinkSelectionRequired` - Check if product cannot be purchased with no links selected.
+*   `getSamples` - Get downloadable product samples as object Magento\Downloadable\Model\ResourceModel\Sample\Collection.
+*   `hasSamples` - Check if product has samples.
+*   `checkProductBuyState` - Check if product can be bought.
+*   `getOrderOptions` - Prepare additional options/information for the order item which will be created from this product as an array.
+*   `getSearchableData` - Retrieve additional searchable data from type instance. Using based on product id and store_id data. (@param `Magento\Catalog\Model\Product` $product).
+*   `isSalable` - Same as Simple.
+*   `processBuyRequest` - Prepare selected options for downloadable products. (@param `Magento\Catalog\Model\Product` $product, @param `Magento\Framework\DataObject` $buyRequest). Returns an array.
+*   `canConfigure` - Check if downloadable product has links and they can be purchased separately.
+*   `hasWeight` - Returns false.
+*   `deleteTypeSpecificData` - Delete data specific for Downloadable product type such as samples and links.
+
+![Magento Section Chevron](./images/icon-chevron.png) Giftcard (`Magento\GiftCard\Model\Catalog\Product\Type\Giftcard`):
+
+> Extends `Magento\Catalog\Model\Product\Type\AbstractType` to provide the following additional methods:
+
+*   `isTypeCombined` - Check if gift card type is combined (Both Physical & Virtual).
+*   `isTypePhysical` - Check if gift card type is physical (a tangible product).
+*   `isTypeVirtual` - Check if gift card type is virtual i.e online voucher only.
+*   `isVirtual` - false for Combined & Virtual, true for Virtual Gift Cards (obviously).
+*   `isSalable` - As well as default isSalable, this checks if there is an existing balance on this gift card.
+*   `checkProductBuyState` - Check if product can be bought
+*   `processBuyRequest` - Prepare selected options for Gift Card (@param `Magento\Catalog\Model\Product` $product, @param `Magento\Framework\DataObject` $buyRequest). Returns an array.
+*   `deleteTypeSpecificData` - Does nothing.
+
+![Magento Exam Information](./images/icon-info.png)It is worth mentioning that `getRelationInfo`, `getAssociatedProducts`, `getChildrenIds`, `getParentIdsByChild`, etc. methods return empty arrays, even though they are shared by all product types, not only compound ones, like Simple and Virtual. The logic of these methods is realized in the compound types' classes, taking into account this type's specifics.
+
+7.2 Describe price functionality
+--------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**Identify the basic concepts of price generation in Magento.**
+
+> Magento is able to operate with a variety of prices, taxes, and product types. Magento represents these prices as Price Types (e.g. final price, minimum price, maximum price, regular price) and are separate from the actual price in the code. For example, Special Price is represented by the final price type in the code. Each type of price has its own class, which is responsible for calculating the total value of this price.
+>
+> Price Info holds Price Collections and is available for all the product types. Price Collections hold pools known as Price Pools which are responsible for instantiating Price Interfaces & Adjustment Collections for each Price Type (final_price, special_price etc)- these pools are defined in the di.xml and are unique to each dedicated product type module and is therefore different for each product type.
+>
+> Adjustment Collections hold Adjustment Pools which are codes that hold relevant Tax information such as wee_tax i.e. fixed product tax (FPT) or tax percentage.
+
+![Magento Exam Information](./images/icon-info.png)Do remember this!
+
+![Magento Section Chevron](./images/icon-chevron.png)Price Info Calculation Flow
+
+> Each product type Price Info implements `Magento\Framework\Pricing\SaleableInterface` How Price Info is calculated:
+
+*   A Price Info Factory specific to product type is created (`Magento\Framework\Pricing\PriceInfo\Factory::create`) and is passed the Price Pool - Each product type has a personal Price Collection and Price Pool instances.
+*   Firstly, the Default Price Info is calculated first (`Magento\Catalog\Model\Product\Type::getPriceInfo`) ALL product types use the SAME instance class `Magento\Framework\Pricing\PriceInfo\Base` to calculate base_price initially.
+*   Secondly, the Adjustment Collections (tax) are calculated (`Magento\Framework\Pricing\Adjustment\Collection`). Again this is the same across all products (it is worth noting that bundle products hold a custom copy of this class but have NO changes. So it's just a separate copy).
+*   Thirdly, the Price Collection loads separate Price Pools of each product type via a code e.g. configurable:
+    *   Price Pool is first calculated (`Magento\Framework\Pricing\Price\Pool`) which iterates through di.xml of each dedicated product type.
+        *   The `<argument>` node named "target" within the `<virtualType>` Price Pool means to inherit prices from other Price Pools e.g: `<argument name="target" xsi:type="object">Magento\Catalog\Pricing\Price\Pool</argument>`
+        * Here are a list of all the available Price Pools:
+            *   `Magento\Catalog\Model\Product\Type\Pool`
+            *   `Magento\Bundle\Pricing\Price\Pool`
+            *   `Magento\ConfigurableProduct\Pricing\Price\Pool`
+            *   `Magento\Downloadable\Pricing\Price\Pool`
+            *   `Magento\GroupedProduct\Pricing\Price\Pool`
+            *   `Magento\GiftCard\Pricing\Price\Pool`
+
+![Magento Section Chevron](./images/icon-chevron.png)Price Types
+
+> Here are all the available Price Types:
+
+*   `base_price` = (`Magento\Catalog\Pricing\Price\BasePrice`) - The minimum product price at the default exchange rate (currency).
+*   `regular_price` = (`Magento\Catalog\Pricing\Price\RegularPrice`) - Product price at the chosen exchange rate (currency).
+*   `final_price` = (`Magento\Catalog\Pricing\Price\FinalPrice`) - Total product price including all discounts, tax and configurations applied.
+*   `special_price` = (`Magento\Catalog\Pricing\Price\SpecialPrice`) - Product price with a discount specific to that product applied (i.e. not a catalog price rule).
+*   `tier_price` = (`Magento\Catalog\Pricing\Price\TierPrice`) - Product price depending on the number of products in the cart and customer group.
+*   `custom_option_price` = (`Magento\Catalog\Pricing\Price\CustomOptionPrice`) - Price of custom options individually, if the product has options (is composite), option price can be displayed in percentage (except for configurable products).
+*   `configured_price` = (`Magento\Catalog\Pricing\Price\ConfiguredPrice`) - Product price together with custom options.
+*   `wishlist_configured_price` = (`Magento\Catalog\Pricing\Price\ConfiguredPrice`) - Product price together with custom options in a wishlist (same logic as configured_price).
+*   `catalog_rule_price` = (`Magento\CatalogRule\Pricing\Price\CatalogRulePrice`) - Product price after catalog rules are applied.
+*   `catalog_rule_price` (content staging) = (`Magento\CatalogRuleStaging\Pricing\Price\CatalogRulePrice`) - create, preview, and schedule a catalog price rule.
+*   `link_price` = (`Magento\Downloadable\Pricing\Price\LinkPrice`) - The price when the product is downloaded from the link provided.
+*   `bundle_option` = (`Magento\Bundle\Pricing\Price\BundleOptionPrice`) - Price of bundle product option individually.
+*   `bundle_option_regular_price` = (`Magento\Bundle\Pricing\Price\BundleOptionRegularPrice`) - Bundle option price together with product final price
+*   `msrp_price` = (`Magento\Msrp\Pricing\Price\MsrpPrice`) - An Adjustment Collection, Manufacturer's Suggested Retail Price (MSRP).
+
+> Each product type might overwrite each Price Type within their Price Pool. A description on how each Price Type has been changed can be found below in the next section.
+
+![Magento Exam Information](./images/icon-info.png)Price bundle_selection = Price of selected bundle product options. While important, is NOT a price type. Rather, a separate entity.
+
+![Magento Exam Information](./images/icon-info.png)Do remember this!
+
+![Magento Section Chevron](./images/icon-chevron.png)Price Pools
+
+> Basic classes, accountable for different price types realisation, are located in `Magento\Catalog\Pricing\Price` namespace and extends `Magento\Framework\Pricing\Price\AbstractPrice`. Different product types, as a rule, override the calculation logic for various price types. In this case, the corresponding classes are located in the names area of the corresponding product types. Also, several product types add custom price types. Let's take a look at Price Pools specific to certain product types:
+
+*   [Simple Products](#h.cbgifdse6zd5) (default) => `Magento\Catalog\Pricing\Price\Collection` => `Magento\Catalog\Pricing\Price\Pool`:
+
+*   `regular_price` (description above)
+*   `final_price` (description above)
+*   `tier_price` (description above)
+*   `special_price` (description above)
+*   `base_price` (description above)
+*   `custom_option_price` (description above)
+*   `configured_price` (description above)
+*   `wishlist_configured_price` (description above)
+*   `catalog_rule_price` (description above)
+*   `catalog_rule_price` (content staging) (description above)
+
+*   [Downloadable Products](#h.614rvm49j6y9) (downloadable) => Magento\Downloadable\Pricing\Price\Collection => Magento\Downloadable\Pricing\Price\Pool:
+
+*   `link_price` (description above)
+*   `wishlist_configured_price` (`Magento\Wishlist\Pricing\ConfiguredPrice\Downloadable`) (description above).
+*   `inherit` rest from default (above).
+
+*   [Configurable Products](#h.98cgcmsgdbu5) (configurable) => `Magento\ConfigurableProduct\Pricing\Price\Collection` => `Magento\ConfigurableProduct\Pricing\Price\Pool`:
+
+*   `regular_price` (`Magento\ConfigurableProduct\Pricing\Price\ConfigurableRegularPrice`) - Get the minimum regular_price from [Associated Simple Products](#h.98cgcmsgdbu5).
+*   `final_price` (`Magento\ConfigurableProduct\Pricing\Price\FinalPrice`) - Get the minimum final_price from [Associated Simple Products](#h.98cgcmsgdbu5).
+*   `wishlist_configured_price` Get the maximum `wishlist_configured_price` from [Associated Simple Products](#h.98cgcmsgdbu5).
+*   inherit rest from default (above).
+
+*   [Bundle Products](#h.41g7zcfrlmri) (bundle) => `Magento\Bundle\Pricing\Price\Collection` => `Magento\Bundle\Pricing\Price\Pool`:
+
+*   `regular_price` (`Magento\Bundle\Pricing\Price\BundleRegularPrice`) - Get the minimum regular_price from [all Selected Options](#h.41g7zcfrlmri).
+*   `final_price` (`Magento\Bundle\Pricing\Price\FinalPrice`) - Get the minimum final_price from [all Selected Options](#h.41g7zcfrlmri).
+*   `tier_price` (`Magento\Bundle\Pricing\Price\TierPrice`) - Calculate tier_price of each [all Selected Options](#h.41g7zcfrlmri).
+*   `special_price` (`Magento\Bundle\Pricing\Price\SpecialPrice`) - Percentage discount off regular_price for each [all Selected Options](#h.41g7zcfrlmri).
+*   `custom_option_price` (`Magento\Catalog\Pricing\Price\CustomOptionPrice`) - (description above).
+*   `base_price` (`Magento\Catalog\Pricing\Price\BasePrice`) - (description above).
+*   `configured_price` (`Magento\Bundle\Pricing\Price\ConfiguredPrice`) - Get configured_price which is the included amount for [all Selected Options](#h.41g7zcfrlmri).
+*   `bundle_option`
+*   `bundle_option_regular_price`
+*   `catalog_rule_price` (`Magento\CatalogRule\Pricing\Price\CatalogRulePrice`) - (description above).
+*   `wishlist_configured_price` (`Magento\Bundle\Pricing\Price\ConfiguredPrice`) - same as configured_price.
+
+*   [Grouped Products](#h.pedurdgu5za5) (grouped) => `Magento\GroupedProduct\Pricing\Price\Collection` => `Magento\GroupedProduct\Pricing\Price\Pool`:
+
+*   `final_price` (`Magento\GroupedProduct\Pricing\Price\FinalPrice`) - Get the minimum final_price from [Associated Simple Products](#h.pedurdgu5za5).
+*   `configured_price` (`Magento\GroupedProduct\Pricing\Price\ConfiguredPrice`) - Rewrite configured_price to calculate the prices of custom options ONLY for all [Associated Simple Products](#h.pedurdgu5za5) of the group as well as custom options.
+*   `configured_regular_price` (`Magento\GroupedProduct\Pricing\Price\ConfiguredRegularPrice`) - Rewrite the configured_regular_price to calculate the prices of custom options + product final price for [Associated Simple Products](#h.pedurdgu5za5) of the group as well as custom options.
+
+*   [Giftcard Products](#h.87l1vab27p5t) (giftcard) => `Magento\GiftCard\Pricing\Price\Collection` => `Magento\GiftCard\Pricing\Price\Pool`:
+
+*   `regular_price` (`Magento\Catalog\Pricing\Price\RegularPrice`) - (description above).
+*   `final_price` (`Magento\GiftCard\Pricing\Price\FinalPrice`) - The Giftcard amount is converted into a regular_price specific to that store's/websites currency.
+*   `tier_price` (`Magento\Catalog\Pricing\Price\TierPrice`) - (description above).
+*   `special_price` (`Magento\Catalog\Pricing\Price\SpecialPrice`) - (description above).
+*   `msrp_price`
+*   `custom_option_price` (`Magento\Catalog\Pricing\Price\CustomOptionPrice`) - (description above).
+*   `base_price` (`Magento\Catalog\Pricing\Price\BasePrice`) - (description above).
+*   `configured_price` (`Magento\GiftCard\Pricing\Price\ConfiguredPrice`) - Price value of product with configured options.
+*   `bundle_option` (`Magento\Bundle\Pricing\Price\BundleOptionPrice`) - (description above).
+*   `wishlist_configured_price` (`Magento\GiftCard\Pricing\Price\ConfiguredPrice`) - Same as configured_price for wishlist.
+
+> Each price type has the `getValue()` and `getAmount()` methods. `getValue()` method returns the price value (`regular_price`), while `getAmount()` method returns the final price (`final_price`) with all the taxes/discounts/configurations applied.
+
+*   Other Price Types
+    *   `index_price` - Product's latest base_price to be updated by indexers.
+    *   `abstract_price` - The default value set in admin (same as base_price if multi-store doesn't exist).
+
+![Magento Section Chevron](./images/icon-chevron.png)Price Pool Example (vendor/magento/module-catalog/etc/di.xml)
+
+```xml
+<virtualType name="Magento\Catalog\Pricing\Price\Pool" type="Magento\Framework\Pricing\Price\Pool">
+    <arguments>
+        <argument name="prices" xsi:type="array">
+            <item name="regular_price" xsi:type="string">Magento\Catalog\Pricing\Price\RegularPrice</item>
+            <item name="final_price" xsi:type="string">Magento\Catalog\Pricing\Price\FinalPrice</item>
+            <item name="tier_price" xsi:type="string">Magento\Catalog\Pricing\Price\TierPrice</item>
+            <item name="special_price" xsi:type="string">Magento\Catalog\Pricing\Price\SpecialPrice</item>
+            <item name="base_price" xsi:type="string">Magento\Catalog\Pricing\Price\BasePrice</item>
+            <item name="custom_option_price" xsi:type="string">Magento\Catalog\Pricing\Price\CustomOptionPrice</item>
+            <item name="configured_price" xsi:type="string">Magento\Catalog\Pricing\Price\ConfiguredPrice</item>
+            <item name="configured_regular_price" xsi:type="string">Magento\Catalog\Pricing\Price\ConfiguredRegularPrice</item>
+        </argument>
+    </arguments>
+</virtualType>
+```
+
+![Magento Exam Question](./images/icon-question.png)**How would you identify what is composing the regular price of the product?**
+
+The regular_price (`Magento\Catalog\Pricing\Price\RegularPrice`) is the raw amount applied to all product types for that currency of that store. If the current store IS NOT multi-store, then use base_price (`Magento\Catalog\Pricing\Price\BasePrice`).
+
+It is calculated using the following methods:
+
+*   `Magento\Catalog\Pricing\Price\RegularPrice::getValue` - Get the minimum float value of that product for that specific store currency.
+*   `Magento\Framework\Pricing\PriceInfoInterface::getPrice` - Convert to display currency. This is raw float value without Price Adjustments (tax).
+*   `Magento\Framework\Pricing\Adjustment\Calculator::getAmount`:
+    *   `Magento\Framework\Pricing\PriceInfoInterface::getAdjustments` -
+    *   Retrieve Price Adjustments (tax) to be included/excluded in either `base_price` or in display price.
+    *   if included in base price:
+        *   `Magento\Framework\Pricing\Adjustment\AdjustmentInterface::extractAdjustment` - get base price without Price Adjustment.
+        *   `Magento\Framework\Pricing\Adjustment\AdjustmentInterface::applyAdjustment` - add Price Adjustment back
+        *   If included in display price:
+            *   `Magento\Framework\Pricing\Adjustment\AdjustmentInterface::applyAdjustment` - add Price Adjustment over base price.
+
+> Alternatively you can also list all the price types available/applied for a specific product by executing the following:
+
+```php
+/** @var \Magento\Framework\Pricing\Price\PriceInterface */
+$prices = $product
+    ->getPriceInfo()
+    ->getPrices();
+```
+
+![Magento Exam Question](./images/icon-question.png)**How would you identify what is composing the final price of the product?**
+
+> Each Price Pool is defined in the di.xml by the individual module of a product type. The final price is calculated by the final_price item within this pool. Price Pools hold the Price Interfaces for every Price Type. Below is a list of the `final_price` per product type:
+
+![Magento Section Chevron](./images/icon-chevron.png) Simple (default) (`Magento\Catalog\Model\Product\Type\Price::calculatePrice`)
+
+> For [Simple](#h.cbgifdse6zd5) and [Virtual](#h.t3fkw0wf3trp) product types, `final_price` delegates calculation to `base_price` minimum value return from all classes implementing `Pricing\Price\BasePriceProviderInterface` - they are:
+
+*   `regular_price` (or base_price if multi-store doesn't exist).
+*   `configured_price` (custom_option_price with selected options configured).
+*   `catalog_rule_price` (final_price vs final_price & catalog_rule_price - whichever is smallest).
+*   `special_price` (final_price vs final_price & special_price - whichever is smallest).
+*   `tier_price`
+
+![Magento Exam Information](./images/icon-info.png)All prices in magento worked on the "least price" approach.
+
+![Magento Exam Information](./images/icon-info.png)Special Price will only be applied if it is lower than Tier Price & Regular Price.
+
+![Magento Section Chevron](./images/icon-chevron.png) Configurable (configurable) (`Magento\ConfigurableProduct\Pricing\Price\FinalPrice`)
+
+> For configurable products, the price of each option is selected as a minimal value from the following calculation of all [Associated Simple Products](#h.98cgcmsgdbu5) combined:
+
+*  `base_price`
+*  `tier_price`
+*  `index_price`
+*  `catalog_rule_price`
+
+> Remember that configurable products themselves hold no price value, it's the associated simple products that do.
+>
+> When choosing the minimum price, the status of the [Associated Simple Product](#h.98cgcmsgdbu5) option, its availability for a particular website and it's stock availability are checked.
+>
+> After determining the final_price of all options, the final price of the configurable product is determined, which will be equal to the lowest cost of its options.
+
+![Magento Section Chevron](./images/icon-chevron.png) Bundle (bundle) (`Magento\Bundle\Model\Product\Price::getFinalPrice`)
+
+> The final_price method is determined by:
+
+*   `Magento\Bundle\Pricing\Price\FinalPrice`
+*   `Magento\Bundle\Pricing\Adjustment\Calculator`
+*   `Magento\Bundle\Pricing\Price\BundleOptionRegularPrice`
+*   `Magento\Bundle\Pricing\Price\BundleOptionPrice`
+*   `Magento\Bundle\Pricing\Price\BundleSelectionPrice`
+
+> Price is calculated the same way for Bundle as for Simple Products (default final price (min of classes implementing interface `BasePriceProviderInterface`) + `bundle_option`:
+
+*   Minimum regular_price (or base_price if multi-store doesn't exist) of the individual product in the bundle.
+*   `configured_price` (custom_option_price with selected options configured) of the individual product in the bundle.
+*   `catalog_rule_price` (`final_price` vs `final_price` & `catalog_rule_price` - whichever is smallest) of the individual product in the bundle.
+*   `special_price` (`final_price` vs `final_price` & `special_price` - whichever is smallest) of the individual product in the bundle.
+*   `tier_price` of the individual product in the bundle.
+*   `bundle_option` - the cost of all required options multiplied by their number.
+
+> Remember that [Bundle Products](#h.41g7zcfrlmri) themselves hold no price value, it's their product bundle options that do.
+>
+> `bundle_option` can be a fixed value or dynamic value (percentage) in which case a dynamic calculation would look like:
+
+```
+Price = `final_price` * (`bundle_option` / 100);
+Price *= Selection Quantity ?: 1
+```
+
+![Magento Section Chevron](./images/icon-chevron.png) Virtual (virtual) (`Magento\Catalog\Model\Product\Type\Price::calculatePrice`)
+
+> Virtual Products follow the same steps as the Simple Product price calculation (above).
+
+![Magento Section Chevron](./images/icon-chevron.png) Downloadable (`Magento\Downloadable\Model\Product\Price`)
+
+> Downloadable Products follow the same steps as the Simple Product price calculation (above) with the option to add Link Price (`Magento\Downloadable\Pricing\Price\LinkPrice`). If Downloadable Links are set to be purchased separately, prices are added after the calculation of base product price:
+
+*   (same as above) `regular_price` (or `base_price` if multi-store doesn't exist).
+*   (same as above) `configured_price` (`custom_option_price` with selected options configured).
+*   (same as above) `catalog_rule_price` (`final_price` vs `final_price` & `catalog_rule_price` - whichever is smallest).
+*   (same as above) `special_price` (`final_price` vs `final_price` & `special_price` - whichever is smallest).
+*   (same as above) `tier_price`
+*   `link_price` (optional, if links are set as purchased separately).
+
+![Magento Section Chevron](./images/icon-chevron.png) Grouped (grouped) (`Magento\GroupedProduct\Model\Product\Type\Grouped\Price::getFinalPrice`)
+
+> Grouped Products follow the same steps as the Simple Product price calculation (above).
+>
+> For each [Associated Simple Product](#h.pedurdgu5za5)
+>
+> Calculation = the maximum value for each child:
+
+```
+final_price += Associated Product final_price * (custom_option_price ?: 1);
+```
+
+![Magento Section Chevron](./images/icon-chevron.png) Giftcard (giftcard) (`Magento\GiftCard\Pricing\Price\FinalPrice::getAmounts`)
+
+> Take the first available giftcard amount.
+>
+> Giftcard amounts are a Product set as an [Extension Attribute](#h.aqe3c923mrz4) (`Magento\GiftCard\Api\Data\GiftcardAmountInterface[]`) which just provides a single value that gets deducted against the products price when redeemed.
+>
+> Giftcards can only be redeemed on products with prices therefore Grouped, Configurable & Bundle are not included here rather, their Associated Simple Products.
+>
+> The Giftcard amount is converted into a regular_price specific to that store's/websites currency.
+>
+> When being redeemed, amount is then converted into a configured_price in class: `Magento\GiftCard\Pricing\Price\ConfiguredPrice::calculatePrice()` whereby the Simple Product price calculation (same as above) is made + giftcard amount to be redeemed:
+
+*   The product's `regular_price` (or `base_price` if multi-store doesn't exist) is calculated.
+*   (same as above) `configured_price` (`custom_option_price` with selected options configured).
+*   (same as above) `catalog_rule_price` (`final_price` vs `final_price` & `catalog_rule_price` - whichever is smallest).
+*   (same as above) `special_price` (`final_price` vs `final_price` & `special_price` - whichever is smallest).
+*   (same as above) `tier_price`
+*   `custom_option_price` the redeemable giftcard amount is then calculated on top.
+
+![Magento Exam Information](./images/icon-info.png)Giftcards are an Enterprise / Commerce Only Feature
+
+![Magento Exam Question](./images/icon-question.png)**How can you customize the price calculation process?**
+
+![Magento Section Chevron](./images/icon-chevron.png) Create A Price Adjustment
+
+> Create a class that Implements `Magento\Framework\Pricing\Adjustment\AdjustmentInterface`
+>
+> Then configure [Dependency Injection](#h.9ofwnl5q9fnf) (DI) configuration:
+
+`di.xml`
+```xml
+<type name="Magento\Framework\Pricing\Adjustment\Collection">
+   <arguments>
+       <argument name="adjustments" xsi:type="array">
+           <item name="somecode" xsi:type="const">MyVendor\MyModule\Pricing\Adjustment::ADJUSTMENT_CODE</item>
+       </argument>
+   </arguments>
+</type>
+
+<type name="Magento\Framework\Pricing\Adjustment\Pool">
+   <arguments>
+       <argument name="adjustments" xsi:type="array">
+           <item name="somecode" xsi:type="array">
+               <item name="className" xsi:type="string">MyVendor\MyModule\Pricing\Adjustment</item>
+               <item name="sortOrder" xsi:type="string">40</item>
+           </item>
+       </argument>
+   </arguments>
+</type>
+```
+![Magento Section Chevron](./images/icon-chevron.png) Register Price Type
+
+> Follow the same steps as above to register a new Price Type in the default price pool namespace.
+>
+> Implement interface Magento\Framework\Pricing\Price\BasePriceProviderInterface.
+>
+> This new price type can influence the final price if it returns the lowest price.
+
+![Magento Section Chevron](./images/icon-chevron.png) Plugin Interceptor
+
+> [Create a plugin](#h.nc1ow1wmf2km) over necessary native price classes of that Price Type, the calculation process of which you need to modify; for example, around getValue() method.
+
+![Magento Section Chevron](./images/icon-chevron.png) Overwrite Virtual Price Preference
+
+> Replace price class via [Dependency Injection](#h.9ofwnl5q9fnf) (DI) for specific virtual pool.
+>
+> Example:
+
+```xml
+<virtualType name="Magento\Bundle\Pricing\Price\Pool">
+    <arguments>
+        <argument name="prices" xsi:type="array">
+            <item name="regular_price" xsi:type="string">MyVendor\MyModule\Pricing\Price\BundleRegularPrice</item>
+        </argument>
+    <arguments>
+</virtualType>
+```
+
+![Magento Section Chevron](./images/icon-chevron.png) Create A Preference
+
+> Replace price class via [Dependency Injection](#h.9ofwnl5q9fnf) (DI) `<preference>` for specific class.
+
+![Magento Exam Question](./images/icon-question.png)**Describe how price is rendered in Magento.**
+
+![Magento Section Chevron](./images/icon-chevron.png)Price Workflow Breakdown
+
+> Price is rendered using both Global & Local Renderers These renderers call the `_prepareLayout` method which calls on the Price Layout Handle (`catalog_product_prices.xml`) - Each product type has its own version of the Price Layout Handle (`catalog_product_prices.xml`).
+>
+> Within this Price Layout Handle (catalog_product_prices.xml) file is a Renderer Pool `<block>` instance - this is a simple wrapper that holds a separate layout instance and renders of each Price Type. Each renderer will create a Price Box block which then calls on the Price Info flow (above).
+
+![Magento Exam Information](./images/icon-info.png)All Price Boxes are cached.
+
+![Magento Section Chevron](./images/icon-chevron.png)Global / Local Renderers
+
+> A Global Render is provided by default (`product.price.render.default`) in which is present for all pages.
+>
+> Global Render calls method `_prepareLayout` which calls the Renderer Pool, every product type adds its own arguments by product type.
+>
+> Of course, Global can be overwritten to a Local Render specific to displaying price in a designated location. There can be multiple on the same page. When defining, the argument `price_type_code` at least MUST be set.
+>
+> Global Example (`Magento_Catalog::view/base/layout/default.xml`):
+
+```xml
+<block class="Magento\Framework\Pricing\Render" name="product.price.render.default">
+    <arguments>
+        <argument name="price_render_handle" xsi:type="string">catalog_product_prices</argument>
+        <argument name="use_link_for_as_low_as" xsi:type="boolean">true</argument>
+    </arguments>
+</block>
+```
+Local Example (`Module_Catalog::view/frontend/layout/catalog_product_view.xml`):
+
+```xml
+<block class="Magento\Catalog\Pricing\Render" name="product.price.final">
+    <arguments>
+        <argument name="price_render" xsi:type="string">product.price.render.default</argument>
+        <argument name="price_type_code" xsi:type="string">final_price</argument>
+        <argument name="zone" xsi:type="string">item_view</argument>
+    </arguments>
+</block>
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)Renderer Pool
+
+> A shared `<block>` `Magento\Framework\Pricing\Render\RendererPool` defined in `catalog_product_prices.xml`. Data-arguments define the Price Box class, template, amount renderer and adjustment render for each combination of product type and Price Type, or defaults when not customized.
+>
+> Base Renderer Pool Example (`Magento_Catalog::view/base/layout/catalog_product_prices.xml`):
+
+```xml
+<block class="Magento\Framework\Pricing\Render\RendererPool" name="render.product.prices">
+    <arguments>
+        <argument name="default" xsi:type="array">
+            <item name="default_render_class" xsi:type="string">Magento\Catalog\Pricing\Render\PriceBox</item>
+            <item name="default_render_template" xsi:type="string">Magento_Catalog::product/price/default.phtml</item>
+            <item name="default_amount_render_class" xsi:type="string">Magento\Framework\Pricing\Render\Amount</item>
+            <item name="default_amount_render_template" xsi:type="string">Magento_Catalog::product/price/amount/default.phtml</item>
+            <item name="prices" xsi:type="array">
+                <item name="special_price" xsi:type="array">
+                    <item name="render_template" xsi:type="string">Magento_Catalog::product/price/special_price.phtml
+
+                    </item>
+                </item>
+                <item name="tier_price" xsi:type="array">
+                    <item name="render_template" xsi:type="string">Magento_Catalog::product/price/tier_prices.phtml</item>
+                </item>
+                <item name="final_price" xsi:type="array">
+                    <item name="render_class" xsi:type="string">Magento\Catalog\Pricing\Render\FinalPriceBox</item>
+                    <item name="render_template" xsi:type="string">Magento_Catalog::product/price/final_price.phtml</item>
+                </item>
+                <item name="custom_option_price" xsi:type="array">
+                    <item name="amount_render_template" xsi:type="string">Magento_Catalog::product/price/amount/default.phtml</item>
+                </item>
+                <item name="configured_price" xsi:type="array">
+                    <item name="render_class" xsi:type="string">Magento\Catalog\Pricing\Render\ConfiguredPriceBox</item>
+                    <item name="render_template" xsi:type="string">Magento_Catalog::product/price/configured_price.phtml</item>
+                </item>
+            </item>
+        </argument>
+    </arguments>
+</block>
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)Price Box
+
+> All Price Box classes implement `Magento\Framework\Pricing\Render\PriceBoxInterface` - they render templates and can render multiple prices like old price and special price.
+>
+> Each price within a Price Box has its own Amount Render which is rendered by class: `Magento\Framework\Pricing\Render\Amount` (as specified above) and is responsible for the display value and adjustments html of a specific price inside the Price Box.
+>
+> Finally, an Adjustment Render is calculated using classes extending `Magento\Framework\Pricing\Render\AbstractAdjustment` - prices / custom markup adjustments are made by whatever has access to amount render and amount, Tax for example.
+
+
+![Magento Exam Question](./images/icon-question.png)**How would you render price in a given place on the page, and how would you modify how the price is rendered?**
+
+![Magento Section Chevron](./images/icon-chevron.png)Local Renderer
+
+> Include new copy block type `Magento\Catalog\Pricing\Render`, pass required value for price_type_code argument (see above for more info on Global/Local renderer).
+
+![Magento Section Chevron](./images/icon-chevron.png)Renderer Pool
+
+Local Overwriting the Renderer Pool (`render.product.prices`) block locally within the Price Layout Handle (`catalog_product_prices.xml`) for that specific product type / module.
+
+Example (`Magento_ConfigurableProduct::view/base/layout/catalog_product_prices.xml`):
+
+```xml
+<referenceBlock name="render.product.prices">
+    <arguments>
+        <argument name="configurable" xsi:type="array">
+            <item name="prices" xsi:type="array">
+                <item name="tier_price" xsi:type="array">
+                    <item name="render_class" xsi:type="string">Magento\ConfigurableProduct\Pricing\Render\TierPriceBox</item>
+                    <item name="render_template" xsi:type="string">Magento_ConfigurableProduct::product/price/tier_price.phtml</item>
+                </item>
+                <item name="final_price" xsi:type="array">
+                    <item name="render_class" xsi:type="string">Magento\ConfigurableProduct\Pricing\Render\FinalPriceBox</item>
+                    <item name="render_template" xsi:type="string">Magento_ConfigurableProduct::product/price/final_price.phtml</item>
+                </item>
+            </item>
+        </argument>
+    </arguments>
+</referenceBlock>
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)Adjustment Render
+
+> Within the Price Layout Handle (`catalog_product_prices.xml`) Overwriting the Renderer Pool (`render.product.prices`) block. Use data-arguments to customize data for price box, amount renders and adjustment renders with the adjustments: `css_classes`, `price_id`, `price_id_prefix`, `price_id_suffix`.
+>
+> Example (`Magento_Tax::view/base/layout/catalog_product_prices.xml`):
+
+```xml
+<referenceBlock name="render.product.prices">
+    <arguments>
+        <argument name="default" xsi:type="array">
+            <item name="adjustments" xsi:type="array">
+                <item name="default" xsi:type="array">
+                    <item name="tax" xsi:type="array">
+                        <item name="adjustment_render_class" xsi:type="string">Magento\Tax\Pricing\Render\Adjustment</item>
+                        <item name="adjustment_render_template" xsi:type="string">Magento_Tax::pricing/adjustment.phtml</item>
+                    </item>
+                </item>
+            </item>
+        </argument>
+    </arguments>
+</referenceBlock>
+```
+
+7.3 Demonstrate ability to use and customize categories
+-------------------------------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**Describe category properties and features.**
+
+| Feature | Backend Type / Frontend Input | Description |
+| --- | --- | --- |
+| `is_active` | int / YesNo | Is the category enabled/disabled. When disabled category will not appear in the menu and will not be reachable via it's URL. |
+| `position` | int / YesNo | The position of the category in relation to other siblings. |
+| `name` | varchar / Text | The category name. |
+| `description` | varchar / WYSIWYG | The description of this category. |
+| `image_url` | varchar / File | The URL path to the image of this category. |
+| `level` | int / (Drag n' Drop) | How deep this category in relation to the root category within the node tree. |
+| `include_in_menu` | int / YesNo | A switch to choose if this category is included within the site's main navigation menu. |
+| `display_mode` | varchar / Select Dropdown | What should this category display: PRODUCTS = Products only. PAGE = Static blocks only. PRODUCTS_AND_PAGE = Static block and products. |
+| `is_anchor` | int / YesNo | Categories can be Anchored / Unanchored. When Anchored, all products from subcategories "bubble up" and show up in the category listing even when not assigned explicitly. |
+| `available_sort_by` | varchar / Multi-select | Within the category's toolbar, users can select how products are sorted. This setting allows admins to select which sort options are available to the user: position, name, price, sort_ranking. |
+| `default_sort_by` | varchar / Select Dropdown | Like the above setting, this just sets which sort option is selected by default. |
+| `url_key` | varchar / Text | The relative URL path of the category. |
+| `meta_title` | string / Text | HTML element that specifies the title of the category |
+| `meta_keywords` | string / TextArea | Used to give more information to search engines on what the category is about. |
+| `meta_description` | string / TextArea | HTML element that specifies the description of the category (takes description if blank). |
+| `custom_use_parent_settings` | Int / YesNo | Take the design elements from the parent. |
+| `custom_design` | varchar / Select Dropdown | Take on the styling / layout of a specific theme for this category |
+| `page_layout` | varchar / Select Dropdown | Change the root page display layout for this category specifically. Some defaults for example: 1 Column, 2 Columns - Left sidebar, 2 Columns - Right sidebar, 3 Columns etc. |
+| `custom_layout_update` | string / TextArea | Any additional layout handles specific for this category. |
+| `custom_apply_to_products` | Apply the custom designs specified in the "Design" section (of the Admin) to the products. |
+
+![Magento Exam Question](./images/icon-question.png)**How do you create and manage categories?**
+
+> `Magento\Catalog\Api\CategoryRepositoryInterface`
+>
+> C.R.U.D actions on the category object (`Magento\Catalog\Api\Data\CategoryInterface`).
+>
+>
+> `Magento\Catalog\Api\CategoryManagementInterface`
+>
+> Managing the category within the node tree (moving to new parents, getting a total number of sub-categories etc).
+>
+>
+> `Magento\Catalog\Api\CategoryLinkRepositoryInterface`
+>
+> C.R.U.D actions on products assigned to a category (`Magento\Catalog\Api\Data\CategoryProductLinkInterface`).
+>
+> `Magento\Catalog\Api\CategoryLinkManagementInterface`
+>
+> Managing (getting/setting) products assigned to a category (`Magento\Catalog\Api\Data\CategoryProductLinkInterface`).
+>
+> `Magento\Catalog\Api\CategoryListInterface`
+>
+> Searching (`Magento\Framework\Api\SearchCriteriaInterface`) for products assigned to a category.
+>
+> `Magento\Catalog\Api\CategoryAttributeOptionManagementInterface`
+>
+> Getting the list of available options for the dropdown, multi select, checkbox types of a category.
+>
+> `Magento\Catalog\Api\CategoryAttributeRepositoryInterface`
+>
+> Searching (`Magento\Framework\Api\SearchCriteriaInterface`) for category attributes.
+
+![Magento Exam Question](./images/icon-question.png)**Describe the category hierarchy tree structure implementation (the internal structure inside the database).**
+
+> Every category has hierarchy fields: `parent_id`, `level` & `path`.
+>
+>
+> To avoid recursive parent-child traversing, A flat category path is saved for every category. It includes all parents IDs. This allows optimisation when searching for children with a single query.
+>
+> E.g. to search children of category id 2 and knowing its path '1/2', we can get children.
+>
+> Example query:
+
+```sql
+SELECT * FROM catalog_category_entity WHERE path LIKE "1/2/%";
+
++-----------+-----------+--------------+-------+| entity_id | parent_id | path | level |
++-----------+-----------+--------------+-------+
+|         3 |         2 | 1/2/3        |     2 |
+|         4 |         3 | 1/2/3/4      |     3 |
+|         5 |         3 | 1/2/3/5      |     3 |
+|         6 |         3 | 1/2/3/6      |     3 |
+|         7 |         2 | 1/2/7        |     2 |
+|         8 |         7 | 1/2/7/8      |     3 |
+```
+
+![Magento Exam Question](./images/icon-question.png)**What is the meaning of parent_id 0?**
+
+> This is a constant of class: `Magento\Catalog\Model\Category` and this ID is reserved for `ROOT_CATEGORY_ID`
+
+*   `const ROOT_CATEGORY_ID = 0;` Reserved functionality, has only one child.
+*   `const TREE_ROOT_ID = 1;` All store group root categories are assigned to this node.
+
+> These categories are not visible in the admin panel in category management.
+>
+> When creating a Root Category from the admin, `parent_id` is always `TREE_ROOT_ID`.
+>
+> `Magento\Store\Model\Store::getRootCategoryId()`:
+
+*   Use `TREE_ROOT_ID` when the store group is not selected.
+*   Each store group has its own Root Category ID.
+*   Each store group Root Category allows only selecting from categories with parent_id = `TREE_ROOT_ID`
+
+![Magento Exam Question](./images/icon-question.png)**How are paths constructed?**
+
+> A forward slash delimiter separates the parents ID from the own ID (see above question on category hierarchy tree structure for an example).
+
+![Magento Exam Question](./images/icon-question.png)**Which attribute values are required to display a new category in the store?**
+
+> The following category attributes are required in order to display a Category in the frontend:
+
+*   `is_active` = 1
+*   `include_in_menu` = 1 - but even if set to 0, it can still be opened via direct link.
+*   `url_key` - Can be created automatically based on name.
+
+![](./images/magento2-category-required-attribute-values.png)
+
+![Magento Exam Question](./images/icon-question.png)**What kind of strategies can you suggest for organizing products into categories?**
+
+> The strategy of organizing products into categories usually depends on the specifics of your online shop, and it's where not only developers, but marketing specialists step into the game.
+>
+> You can organize items into categories according to the target group of buyers (men, women, children, etc.) or their purpose (tourism, fitness, running, etc.) or whichever logic you believe is the most suitable. But please bear in mind that the products should share common attributes, based on which you will create a filter, like shirt size or color.
+
+![Magento Exam Information](./images/icon-info.png)This is a very weird question and more of a Solution Specialist question, not a developer one.
+
+7.4 Determine and manage Catalog / Cart Price Rules
+---------------------------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**How would you create a Catalog Price Rule?**
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Catalog Price Rules
+
+> Catalog price rules can be used to offer products to buyers at a discounted price, based on a set of defined conditions. Catalog price rules do not use coupon codes, because they are triggered before a product is placed into the shopping cart.
+
+![Magento Section Chevron](./images/icon-chevron.png)Catalog Price Rule
+
+| Attribute | Backend Type / Frontend Type | Description |
+| --- | --- | --- |
+| `name` | varchar/Text | (Required) The name of the rule is for internal reference. |
+| `description` | varchar/TextArea | A description of the rule should include the purpose of the rule, and explain how it is used. |
+| `is_active` | int/YesNo | (Required) Determines if the rule is currently active in the store. Options: Yes / No |
+| `website_ids` | varchar/Multiselect | (Required) Identifies the websites where the rule can be used. |
+| `customer_group_ids` | varchar/Multiselect | (Required) Identifies the customer groups to which the rule applies. |
+| `sort_order` | int/Number | The Priority setting is important when the same catalog product meets the conditions set for more than one price rule. The rule with the highest Priority setting (1 being the highest) will become active for the product. |
+| `discount_amount` (Action section) | int/Number | (Required) The amount of discount that is offered. |
+| `stop_rules_processing` (Action section) | int/YesNo | Determines if additional rules can be applied to this purchase. To prevent multiple discounts from being applied to the same purchase, select Yes. Options: Yes / No |
+| `from_time` (community/open source only) | datetime/DatePicker | The first date the coupon can be used. |
+| `to_time` (community/open source only) | datetime/DatePicker | The last date the coupon can be used. |
+
+![Magento Section Chevron](./images/icon-chevron.png)Catalog Price Rule Conditions
+
+| Condition | Description |
+| --- | --- |
+| Conditions Combination | Choose to create an additional set of All/Any and True/False conditions inside the existing condition. |
+| Product Attributes | Attribute Set, Category SKU. For an attribute to appear in the list, it must be configured to be Used In Promo Rule Conditions. To learn more, see [](https://docs.magento.com/user-guide/stores/attributes-product.html&sa=D&ust=1609223265581000&usg=AOvVaw2uICv2INQwdEIzLWgCqXW1) [Product Attributes](https://docs.magento.com/user-guide/stores/attributes-product.html&sa=D&ust=1609223265581000&usg=AOvVaw2uICv2INQwdEIzLWgCqXW1). |
+
+![Magento Section Chevron](./images/icon-chevron.png)Catalog Price Rule Actions
+
+| Action (simple_action) | Description |
+| --- | --- |
+| Apply as percentage of original | Discounts item by subtracting a percentage of the regular price. For example: Enter 10 in Discount Amount for a final price that is marked down 10% from the regular price. |
+| Apply as fixed amount | Discounts item by subtracting a fixed amount from the regular price. For example: Enter 10 in Discount Amount for a final price that is $10 less than the regular price. |
+| Adjust final price to this percentage | Adjusts the final price by a percentage of the regular price. For example: Enter 50 in Discount Amount for a final price that is marked down 50% from the regular price. |
+| Adjust final price to discount value | Sets the final price to a fixed, discounted amount. For example: Enter 20 in Discount Amount for a final price of $20.00. |
+
+![Magento Exam Information](./images/icon-info.png)Regular price refers to the base product price without any advanced pricing (special/tier/group) or promotional discounts. Final price refers to the discounted price that appears in the shopping cart.
+
+For more information on Catalog Price Rules, see here:
+
+[https://docs.magento.com/user-guide/marketing/price-rules-catalog-create.html](https://docs.magento.com/user-guide/marketing/price-rules-catalog-create.html&sa=D&ust=1609223265584000&usg=AOvVaw0zR3Yoa46w__Dc4XvB5Gcz)
+
+![Magento Section Chevron](./images/icon-chevron.png)Related Dynamic Blocks
+
+Identifies any dynamic block(s) that are associated with the rule.
+
+![Magento Section Chevron](./images/icon-chevron.png)Manage Coupon Codes
+
+Coupons codes are used with [](https://docs.magento.com/user-guide/marketing/price-rules-cart.html&sa=D&ust=1609223265585000&usg=AOvVaw3UwrOOyGrxfY24gc4tsq8m) [Cart Price Rules](https://docs.magento.com/user-guide/marketing/price-rules-cart.html&sa=D&ust=1609223265586000&usg=AOvVaw3_xvXtinqn2nDJMe6qEd8h) to apply a discount when a set of conditions is met. For example, a coupon code can be created for a specific customer group, or for anyone who makes a purchase over a certain amount. To apply the coupon to a purchase, the customer can enter the coupon code in the cart, or possibly at the cash register of your brick and mortar store. Here are a few ways that you can use coupons in your store:
+
+*   Email coupons to customers
+*   Produce printed coupons
+*   Create in-store coupons for mobile users
+
+More info now how to create Cart Price Rules here:
+
+[https://docs.magento.com/user-guide/marketing/price-rules-cart-create.html](https://docs.magento.com/user-guide/marketing/price-rules-cart-create.html&sa=D&ust=1609223265587000&usg=AOvVaw20yqJJfKPJBKp_3ErxPY8q)
+
+![Magento Exam Question](./images/icon-question.png)**How are Catalog Price Rules saved?**
+
+![Magento Section Chevron](./images/icon-chevron.png)Catalog Rules - Repository
+
+> Managing (C.R.U.D actions) rules is done using the [Service Contract](#h.i0qq8aqgijv7) design pattern with the following class:
+
+```php
+Magento\CatalogRule\Api\CatalogRuleRepositoryInterface::save(
+    \Magento\CatalogRule\Api\Data\RuleInterface $rule
+);
+```
+
+Rule Conditions has it's own [Custom Attribute](#h.2lcvcwr56aq) class:
+
+Magento\CatalogRule\Api\Data\ConditionInterface
+
+![Magento Section Chevron](./images/icon-chevron.png)Catalog Rules - Database
+
+Primary Tables:
+
+*   `catalogrule` - The main entity table holding information specific to rules. Main features of this table:
+
+    *   Dates from/to
+    *   Conditions (serialized)
+    *   Actions serialized
+    *   Stop further processing
+    *   Simple action
+    *   Discount amount
+
+*   `catalogrule_product` - These are the products which apply to each rule, they are updated by the indexers. Main features of this table:
+
+    *   Time from/to
+    *   Product ID
+    *   Action amount / operator / stop
+
+*   `catalogrule_website` - Just a relational table between the Catalog Rule and which Website in which it is applied. The only features of this table are:
+
+    *   Rule ID
+    *   Website ID
+
+*   `catalogrule_product_price` - A relational table between Product, Price, Customer Group & Rule updated by the indexers. Product prices demand their own table due to the natural complexity of it. Main features of this table:
+
+    *   Customer Group ID`
+    *   Product ID
+    *   Rule date
+    *   Rule price
+    *   Latest start date
+    *   Earliest end date`
+
+*   `catalogrule_customer_group` - Another relational table between the Catalog Rule and which Customer Group in which it is applied. The only features of this table are:
+
+    *   Rule ID
+    *   Customer Group ID
+
+*   `catalogrule_group_website` - Just another relational table between Catalog Rule to Customer Group & Website that currently exists in the index table. Only features of this table:
+
+    *   Rule ID
+    *   Customer group ID
+    *   Website ID
+
+*   `sequence_catalogrule` - A number dedicated to incrementing the Catalog Rule IDs by. Only item in this table:
+
+    *   Sequence Value - The value to increment the ID by
+
+*   `magento_banner_catalogrule` (Magento Commerce/Enterprise only) - Used for [Dynamic Blocks in Price Rules](https://docs.magento.com/user-guide/cms/dynamic-blocks-price-rules.html&sa=D&ust=1609223265594000&usg=AOvVaw1S8GOz-r4cpDWs8ZYzz8Sf). Only features of this table:
+
+    *   Banner ID
+    *   Rule ID
+
+*   `magento_reward_salesrule` (Magento Commerce/Enterprise only) - Used for [Reward Points can be awarded to customers on the basis of a Cart Price Rule](https://docs.magento.com/user-guide/marketing/reward-points-price-rules.html&sa=D&ust=1609223265595000&usg=AOvVaw0moqpJ1r6z3RPTrd2nxqak). The award of points can be the only action of the price rule, or can be used in combination with a discount.
+
+
+Indexer Tables
+
+*   `catalogrule_rule_cl` - Catalog Product Rule change-log table is responsible for  catalog rule "conditions". If a "condition" is updated (like a 10% discount or something), this table gets populated with the changes, the indexer gets invalidated pending a re-run ready to update catalogrule. Only features of this table:
+
+    *   Version ID of Materialized View (mview)
+    *   Rule Entity ID
+
+*   `catalogrule_product_cl` - Catalog Rule Product change-log table is responsible for updating the products on which catalog rule will be applied. This table is populated with the changes ready to update catalogrule_product when the indexer runs. Only features of this table:
+
+    *   Version ID of Materialized View (mview)
+    *   Rule Entity ID
+
+
+Replica Tables
+
+> Replica tables are mainly used for indexer optimization. Replica tables are used to prevent deadlocks or wait locks caused by read/write collisions on the same table. Magento uses a separate table for reading/writing operations and indexing. As a result of this "switching" process, the customer can freely navigate the front-end, search pages, use layered navigation filtered with price, whilst you run a full re-index. The replica tables associated with Catalog Rule Product are:
+
+*   `catalogrule_product_replica`
+*   `catalogrule_product_price_replica`
+*   `catalogrule_group_website_replica`
+
+![Magento Exam Question](./images/icon-question.png)**When would you use Catalog Price Rules?**
+
+> There are infinite answers to this question, here are some examples:
+
+*   Setting up a discount on a category for an occasion or end of line.
+*   VIP customer group members get X amount off.
+*   For a B2B website, discount 10% from all prices.
+*   Wholesale
+
+> The point is that discounts on the Catalog for numerous conditions exist in Magento to suit a wide variety of business goals.
+
+![Magento Exam Information](./images/icon-info.png)This is a very weird question and more of a Solution Specialist question, not a developer one.
+
+![Magento Exam Question](./images/icon-question.png)**When would you use Cart Price Rules?**
+
+> There are infinite answers to this question, here are some examples:
+
+*   Creating a coupon or voucher code to use as a marketing strategy.
+*   Buy X get Y free.
+*   Free shipping over a certain amount.
+*   Discount on over $100 orders.
+
+> The point is that discounts on the Cart/Sales for numerous conditions exist in Magento to suit a wide variety of business goals.
+
+![Magento Exam Information](./images/icon-info.png)This is a very weird question and more of a Solution Specialist question, not a developer one.
+
+![Magento Exam Question](./images/icon-question.png)**How does Catalog Price Rules impact performance?**
+
+> The impact on page loading is relatively small, since all price calculations occur during reindex. The speed of reindex is affected by: the number of catalog rules, customer groups, products and websites affected. In the worst case, if all catalog price rules affect all customer groups, products and websites, then the number of rows in the catalogrule_product table will be CATALOG_RULES_QTY * CUSTOMER_GROUPS_QTY * PRODUCTS_QTY * WEBSITES_QTY. The catalogrule_product_price table contains 3 times more rows than the catalogrule_product table.
+>
+> Example:
+>
+> We have one catalog rule that applies to 4 customer groups, one website and 247 products. In this case, the number of lines in the tables will be the following:
+
+*   `catalogrule_product`: 1 * 4 * 1 * 247 = 988 rows.
+*   `catalogrule_product_price`: 988 * 3 = 2964 rows.
+
+> Why is the influence on the page upload is relatively insignificant?
+>
+> Observer for `catalog_product_get_final_price` in `Magento_Catalog::etc\frontend\events.xml` - it simply requests from the table catalogrule_product_price and assigns the value to the product if a rule exists.
+
+![Magento Exam Question](./images/icon-question.png)**How would you debug problems with Catalog Price Rules?**
+
+1.  First, make sure that price rule is active. Navigate to
+    Admin > Marketing > Promotions > Catalog Price Rule and make sure that the status is set at active.
+2.  Check indexes for catalogrule_product - find row by product id, ensure found - rule matched.
+3.  Ensure needed rule matched and unwanted rules didn't match, check sort_order, check from_time and to_time, ensure correct
+4.  Check the database table: catalogrule_product_price contains product within +-1 day
+5.  Apply the rules by pressing the corresponding button Apply Rules in Admin > Marketing > Promotions > Catalog Price Rule
+
+![Magento Exam Question](./images/icon-question.png)**How would you debug problems with Cart Price Rules?**
+
+1.  First, make sure that price rule is active. Navigate to Admin > Marketing > Promotions > Cart Price Rule and make sure that the status is set at active.
+2.  Ensure needed rules are matched and unwanted rules don't match, check sort_order, check from_time and to_time, ensure correct.
+3.  If conditions based on product attributes check the database table: salesrule_rule_cl contains product entity_id
\ No newline at end of file
diff --git a/8. Customizing the Checkout Process/1. Demonstrate ability to use quote, quote item, address, and shopping cart rules in checkout.md b/8. Customizing the Checkout Process/1. Demonstrate ability to use quote, quote item, address, and shopping cart rules in checkout.md
deleted file mode 100644
index baf536c..0000000
--- a/8. Customizing the Checkout Process/1. Demonstrate ability to use quote, quote item, address, and shopping cart rules in checkout.md	
+++ /dev/null
@@ -1,137 +0,0 @@
-#  Demonstrate ability to use quote, quote item, address, and shopping cart rules in checkout
-
-Interesting *quote* fields or methods:
-- `ext_shipping_info` - TEXT 64k, existed in M1, not used. Good place to keep shipping API response?
-- `trigger_recollect`
-  * quoteResource.markQuotesRecollectOnCatalogRules - Mark quotes that depend on catalog price rules
-    to be recollected on demand. Called on event `catalogrule_before_apply`. Good way to update carts
-    after "hacking" prices?
-  * quoteResource.markQuotesRecollect - by product IDs. Mark recollect contain product(s) quotes
-    + global plugin after product save, _if price or tier price changed_, trigger recollect
-    + adminhtml event after product save, _if status disabled_.
-- `is_changed` - not used
-  * before quote save - see temporary data-attribute quote.`changed_flag` - not used
-- `orig_order_id` -  not used
-- `items_count` - INT "Display number of items in cart"
-- `items_qty` - FLOAT "Display item quantities", e.g. 1.5 kg, 3 same chairs etc.
-- `converted_at` - not used
-- getItemsByProduct - matching product id and custom options. good to use right after add to cart
-  + quote.addProduct
-  + after withlist aded to cart, finds and changes store id
-  + withlist add all to cart, on error find and remove from cart
-
-Quote extends Model\AbstractExtensibleModel - has support of `extension_attributes`.
-Register extensions in `extension_attributes.xml`:
-```xml
-<extension_attributes for="Magento\Quote\Api\Data\CartInterface">
-    <attribute code="shipping_assignments" type="Magento\Quote\Api\Data\ShippingAssignmentInterface[]" />
-</extension_attributes>
-```
-Use quote repository plugins afterLoad, beforeSave or whenever needed to populate your values.
-Quote does not utilize `custom_attributes` as it is not EAV by nature.
-
-Quote address custom attributes:
-* community \Magento\Quote\Model\Quote\Address\CustomAttributeList - empty, use plugin to add
-* EE \Magento\CustomerCustomAttributes\Model\Quote\Address\CustomAttributeList::getAttributes
-  + customer address attributes + customer attributes
-
-Quote Item shares 2 models, quote item and quote address item.
-
-*Quote item* interesting methods:
-- checkData - called after adding to cart and updating options
-  * quote item.setQty - triggers stock validation
-  * product type instance.checkProductBuyState
-- `custom_price`
-- getCalculationPrice - `custom_price` or converted price
-- isChildrenCalculated - product.getPriceType = CALCULATE_CHILD
-- isShipSeparately - product.getShipmentType = SHIPMENT_SEPARATELY
-- `additional_data` - TEXT
-- getOptions
-- getQtyOptions:
-  * for composite products in cart when sub-products are added, returns array something like
-    `[$subProductId = qty (from option `product_qty_{$subProductId}`), otherSubId = qty, ...]`
-    + used in \Magento\CatalogInventory\Model\Quote\Item\QuantityValidator::validate
-- compare - \Magento\Quote\Model\Quote\Item\Compare::compare - merge items and add qty instead of new item
-  + \Magento\Quote\Model\Quote::updateItem
-- representProduct - compares quote item with some new product, checks product id and custom options
-  + quote.getItemsByProduct
-- compareOptions 
-  + representProduct
-
-## Describe how to modify these models and effectively use them in customizations.
-- All support extension attributes
-- Quote address supports custom_attributes
-
-## Inventory validation
-Qty can be updated from:
-- cart model.updateItems by:
-  * checkout/cart/updatePost with update_cart_action='update_qty'
-- quote.updateItem by:
-  * admin/sales/order/create
-  * advanced checkout
-  * checkout/cart/updateItemOptions
-  * admin/cart_product_composite_cart/update
-  * quote repository.save via Savehandler and CartItemPersister
-
-on qty update:
-- quote item.setQty
-- event `sales_quote_item_qty_set_after`
-- \Magento\CatalogInventory\Observer\QuantityValidatorObserver::execute
-- \Magento\CatalogInventory\Model\Quote\Item\QuantityValidator::validate
-  * all validation errors can set quote.addErrorInfo, quote item.addErrorInfo
-  * check out of stock, parent out of stock
-  * when there's sub products with qty options:
-    + check qty increments
-    + for each sub product - initializer option.initialize
-      \Magento\CatalogInventory\Model\Quote\Item\QuantityValidator\Initializer\Option::initialize
-      - multiply parent qty`*`sub qty, check resulting min sale qty, max sale qty, qty increments, in stock, backorders
-        \Magento\CatalogInventory\Model\StockState::checkQuoteItemQty,
-        \Magento\CatalogInventory\Model\StockStateProvider::checkQuoteItemQty
-  * when no sub products qty:
-    + initializer stock item.initialize
-    \Magento\CatalogInventory\Model\Quote\Item\QuantityValidator\Initializer\StockItem::initialize
-    \Magento\CatalogInventory\Model\StockState::checkQuoteItemQty
-    \Magento\CatalogInventory\Model\StockStateProvider::checkQuoteItemQty
-
-## Add to cart
-cart model - deprecated.
-
-- checkout/cart/add [product, qty, related_product]
-  * cart model.addProduct
-    + filter request here, can register own via argument for \Magento\Checkout\Model\Cart\RequestInfoFilter
-    + by default filtered out `form_key` and `custom_price`
-  * quote.addProduct
-  * product type instance.prepareForCartAdvanced
-  * get same quote item or create new
-  * \Magento\Quote\Model\Quote\Item\Processor::prepare
-    + quote item.addQty
-    + support request.customPrice -> quote item.customPrice
-  * event `checkout_cart_product_add_after`
-  * checkout session.setLastAddedProductId
-  * cart.save
-    + quote collect totals
-    + event `checkout_cart_save_after`
-    + reinitialize state - remove addresses and payments
-  * event `checkout_cart_add_product_complete`
-
-- checkout/cart/updatePost
-  * cart.suggestItemsQty => \Magento\CatalogInventory\Model\StockStateProvider::suggestQty - qty increments, min/max qty
-  * cart.updateItems
-    + events `checkout_cart_update_items_before`, `checkout_cart_update_items_after`
-    + quote item.setQty -- triggers stock validation
-  * cart.save
-
-## Describe how to customize the process of adding a product to the cart.
-- plugin over product type `prepareForCartAdvanced`
-- event `catalog_product_type_prepare_full_options` - custom options in `_prepareOptions`
-- plugin over \Magento\Quote\Model\Quote\Item\Processor::prepare - qty, custom price
-- event `checkout_cart_product_add_after`
-
-## Which different scenarios should you take into account?
-- add to cart from catalog
-- add to cart from wishlist
-- move all wishlist to cart
-- merge quote when existing customer has quote, then shops as a guest and logs in
-- admin create order
-- admin reorder
-- configure added product - change custom options
diff --git a/8. Customizing the Checkout Process/2. Demonstrate ability to use totals models.md b/8. Customizing the Checkout Process/2. Demonstrate ability to use totals models.md
deleted file mode 100644
index 6839b22..0000000
--- a/8. Customizing the Checkout Process/2. Demonstrate ability to use totals models.md	
+++ /dev/null
@@ -1,148 +0,0 @@
-# Demonstrate ability to use totals models
-
-sales.xml
-```xml
-<section name="quote">
-    <group name="totals">
-        <item name="tax" instance="Magento\Tax\Model\Sales\Total\Quote\Tax" sort_order="450">
-            <renderer name="adminhtml" instance="Magento\Sales\Block\Adminhtml\Order\Create\Totals\Tax"/>
-            <renderer name="frontend" instance="Magento\Tax\Block\Checkout\Tax"/>
-        </item>
-    </group>
-</section>
-```
-
-Classes:
-- Quote\TotalsCollector - does the job, `collect` and `collectAddressTotals`. (collectQuoteTotals not used)
-
-## Quote totals
-- quote.collectTotals
-- total = totalsCollector.collect - crunch numbers, return data to set on quote
-  * create *quote total object* quote\address\total. all you set here will be copied to quote
-  * event `sales_quote_collect_totals_before`
-  * collect item qtys - quote.itemsCount, quote.itemsQty, quote.virtualItemsQty
-  * zero total object amounts - subtotal, grand total etc.
-  * collect each *address totals*:
-    + *collect address totals* into new address total object
-      - address total = quote.*collectAddressTotals* _(see below)_
-    + *add* to quote total object: shipping amount, shipping description, subtotal, subtotal with discount, grant total
-      (+ base versions when applicable)
-  * validate max grand total amount 99999999
-  * validate coupon code - check that at least one address has it, otherwise reset to '' - code is invalid
-  * event `sales_quote_collect_totals_after`
-- quote.addData(total.getData)
-
-## Address totals
-quote.collectAddressTotals for each address (billing, shipping) - set address fields, return some fields for quote
-- new shipping assignment obj:
-  + shipping = [method, address]
-  + items = address items. empty for normal checkout?
-- create new *address total object* quote\address\total. all you set here will be copied to address
-- event `sales_quote_address_collect_totals_before`
-- get collectors:
-  + _initModels -> _initModelInstance -> model.processConfigArray -- tax collector can change its sort programmaticaly
-  + sales/totals_sort/* - admin configurable *totals retrievers* ordering - display order
-- *every collector[].collect*
-  + all data set on address total object will be copied to address. Main amounts will also copy to quote total object.
-  + has direct access to quote
-  + has access to address via shipping assignment.getShipping.getAddress
-- event `sales_quote_address_collect_totals_after`
-- address.addData(address total.getData)
-
-## Display totals
-Totals rendered in cart in UI-component fashion with JS configuration.
-
-Totals JS models extend `Magento_Checkout/js/view/summary/abstract-total` and implement:
-- getPureValue - raw float
-- getValue - formatted via `Magento_Catalog/js/price-utils` in format `window.checkoutConfig.priceFormat`.
-
-Models get their values from model quote.getTotals(), e.g. `quote.getTotals()().subtotal`.
-Initial totals values are in `window.checkoutConfig.totalsData`, any extended attributes are merged into main totals.
-
-`window.checkoutConfig` values are provided by `\Magento\Checkout\Model\CompositeConfigProvider`.
-Default config provider `\Magento\Checkout\Model\DefaultConfigProvider`.
-Register your classes via arguments.
-
-Default config provider.getTotalsData and REST API reuse same repository.
-\Magento\Quote\Model\Cart\CartTotalRepository::get:
-- billing or shipping address.getTotals
-  * \Magento\Quote\Model\Quote\TotalsReader::fetch
-  * each collector[].*fetch*(quote, data)
-    + can return \Magento\Quote\Model\Quote\Address\Total or array [code, title, value]
-    + title can be object with method *render()* - by default this is just __ Phrase translation
-    + can return multiple totals as once
-    + can overwrite other totals by code
-- convert address data to interface Cart\Totals - totals by code + quote visible items
-- *totals segments* - totals by code as return from fetch:
-  * \Magento\Quote\Model\Cart\TotalsConverter::process - convert address totals to total segment
-  * title = titleRenderer.render
-- add other info - coupon code, grand total, items, items qty, currency code
-
-js model quote.getTotals:
-```
-[
-  {address data fields = populate \Magento\Quote\Api\Data\TotalsInterface with address.getData},
-  items = quote visible items,
-  total_segments = as returned from totals collector.fetch
-]
-```
-
-## Invoice totals, credit memo totals
-```xml
-<section name="order_invoice">
-    <group name="totals">
-        <item name="subtotal" instance="Magento\Sales\Model\Order\Invoice\Total\Subtotal" sort_order="50"/>
-    </group>
-</section>
-<section name="order_creditmemo">
-    <group name="totals">
-        <item name="subtotal" instance="Magento\Sales\Model\Order\Creditmemo\Total\Subtotal" sort_order="50"/>
-    </group>
-</section>
-```
-
-Invoice totals:
-- \Magento\Sales\Model\Order\Invoice::collectTotals
-- every total - \Magento\Sales\Model\Order\Invoice\Total\AbstractTotal::collect(invoice)
-  + directly update invoice object
-
-Credit memo totals:
-- \Magento\Sales\Model\Order\Creditmemo::collectTotals
-- every total - \Magento\Sales\Model\Order\Creditmemo\Total\AbstractTotal::collect
-  + directly update credit memo object
-
-## Render totals in admin area:
-Example - admin invoice totals:
-
-handle `sales_order_invoice_view`:
-```xml
-<block class="Magento\Sales\Block\Adminhtml\Order\Invoice\Totals" name="invoice_totals" template="Magento_Sales::order/totals.phtml">
-```
-
-- block totals.`_beforeToHtml`
-- block order totals.`_initTotals` - add hardcoded totals - subtotal, shipping, discount, grand_total, base_grandtotal
-- every child block.initTotals
-- child blocks call block order totals.addTotal(total, after={'first'|'last'|$code}) or addTotalBefore(total, before)
-  + total = DataObject [code, value, base_value, label, optional: {area, block_name, is_formated, strong}]
-- block order totals template
-  + totals with area = 'footer'
-  + totals with empty area
-  + if 'block_name', getChildHtml - simply renders child block
-  + otherwise print [label, value], value will be price formated unless flag 'is_formated'
-
-
-## Describe how to modify the price calculation process in the shopping cart.
-- when preparing product in product type model, can set `product.custom_price`
-- register quote totals collector in sales.xml. Edit given address_total.
-  Examples:
-  * `$total->setGrandTotal($total->getGrandTotal() - $pointsCurrencyAmountUsed);`
-  * call `$total->addTotalAmount(code, value)`. Grand total will then be sum of all total amounts - they can be negative.
-
-## How can you add a custom totals model or modify existing totals models?
-- add quote totals collector - declare in sales.xml, implement `collect` and `fetch`
-  + in collect can modify address totals object (preferred), or edit directly quote or quote address via shipping assignment
-  + fetch can return null, or one or many declarations in array format or ready Address\Total objects
-  + fetch can rewrite other totals with same 'code'
-  + in cart block JS config, add view model and implement getPureValue, getValue. Can read values from model quote.getTotals().totals_segments
-- Render totals in admin:
-  + sales_invoice_view, referenceBlock 'invoice_totals', add block with method `initTotals`, call parentBlock.`addTotal`
diff --git a/8. Customizing the Checkout Process/3. Demonstrate ability to customize the shopping cart.md b/8. Customizing the Checkout Process/3. Demonstrate ability to customize the shopping cart.md
deleted file mode 100644
index b23cea7..0000000
--- a/8. Customizing the Checkout Process/3. Demonstrate ability to customize the shopping cart.md	
+++ /dev/null
@@ -1,269 +0,0 @@
-# Demonstrate ability to customize the shopping cart
-
-## Describe how to implement shopping cart rules.
-DB tables:
-- `salesrule`
-  * name, description, is_active, is_rss
-  * from_date, to_date, conditions_serialized, is_advanced, sort_order, product_ids
-  * actions_serialized, simple_action, discount_amount, discount_qty, discount_step, apply_to_shipping
-  * stop_rules_processing, uses_per_customer, times_used
-  * coupon_type, use_auto_generation
-- `salesrule_label` - label translation
-  * rule_id, store_id, label
-- `salesrule_product_attribute`
-  * rule_id, website_id, customer_group_id, attribute_id
-
-Multiple selection:
-- `salesrule_website`
-- `salesrule_customer_group`
-
-- `salesrule_coupon`
-  * rule_id, code, usage_limit, usage_per_customer, times_used, expiration_date, is_primary, created_at, type
-
-Usage tracking:
-- `salesrule_coupon_usage`
-  * coupon_id, customer_id, times_used
-- `salesrule_customer`
-  * rule_id, customer_id, times_used
-- `salesrule_coupon_aggregated`, `salesrule_coupon_aggregated_updated`, `salesrule_coupon_aggregated_order` - reporting stuff
-
-Notes:
-- ui component `sales_rule_form`
-- conditions - html content block - *generic form* Edit\Tab\Conditions
-- conditions fieldset renderer \Magento\Rule\Block\Conditions.render
-- `$element->getRule()->getConditions()->asHtmlRecursive();`
-- Magento\SalesRule\Model\Rule extends Magento\Rule\Model\AbstractModel
-  + store labels
-  + coupon generation
-- Conditions model instance - \Magento\SalesRule\Model\Rule\Condition\Combine, extends getNewChildSelectOptions:
-  + \Magento\SalesRule\Model\Rule\Condition\Product\Found - Product attribute combination
-  + \Magento\SalesRule\Model\Rule\Condition\Product\Subselect - Products subselection
-  + Conditions combination - self, recursion
-  + \Magento\SalesRule\Model\Rule\Condition\Address - Cart Attribute:
-    base_subtotal, total_qty, weight, shipping_method, postcode, region, region_id, country_id
-
-what is:
-- `is_advanced` column - not used
-- `product_ids` column - not used
-- `salesrule_product_attribute` table - attributes currently used in conditions and actions of rule.
-
-  Used in plugin to \Magento\Quote\Model\Quote\Config::`getProductAttributes` to ensure all needed
-  attributes are loaded with quote.
-  * quote.load()
-  * quoteResource.`_assignProducts`
-  * product collection `->addAttributeToSelect($this->_quoteConfig->getProductAttributes())`.
-
-
-## What is the difference between sales rules and catalog rules?
-- Catalog rules update product final price, they are visible in all catalog - category listing, product page.
-- Sales rule is visible only in checkout and can require a coupon.
-- Sales rules can affect shipping price
-- Sales rules can trigger on products combination
-
-
-## How do sales rules affect performance?
-Performance is not affected, all calculation happens in totals collectors.
-
-## What are the limitations of the native sales rules engine?
-Only one coupon can be applied.
-
-
-Implementing rules:
-- Rule model
-  * getConditionsInstance - will be used in form as `$model->getConditions()->asHtmlRecursive()`.
-    Usually starting conditions are composite - selector [all/any] and sub-conditions selection.
-- Composite conditions model
-  * getNewChildSelectOptions - used by Consition\Combine.getNewChildElement
-
-
-## Describe add-to-cart logic in different scenarios.
-
-### Add to cart
-cart model - used only on frontend, marked deprecated.
-
-- checkout/cart/add [product, qty, related_product]
-  * cart model.addProduct
-    + filter request here, can register own via argument for \Magento\Checkout\Model\Cart\RequestInfoFilter
-    + by default filtered out `form_key` and `custom_price`
-  * quote.addProduct
-  * product type instance.`prepareForCartAdvanced`
-  * get same quote item or create new
-  * \Magento\Quote\Model\Quote\Item\Processor::prepare
-    + quote item.addQty
-    + support request.customPrice -> quote item.customPrice
-  * event `checkout_cart_product_add_after`
-  * checkout session.setLastAddedProductId
-  * cart.save
-    + quote collect totals
-    + event `checkout_cart_save_after`
-    + reinitialize state - remove addresses and payments
-  * event `checkout_cart_add_product_complete`
-
-- checkout/cart/updatePost
-  * cart.suggestItemsQty => \Magento\CatalogInventory\Model\StockStateProvider::suggestQty - qty increments, min/max qty
-  * cart.updateItems
-    + events `checkout_cart_update_items_before`, `checkout_cart_update_items_after`
-    + quote item.setQty -- triggers stock validation
-  * cart.save
-
-### *controller checkout/cart/add*:
-- cart.addProduct:
-  * quote.addProduct: type.`prepareForCartAdvanced`, event `sales_quote_product_add_after`
-  * event `checkout_cart_product_add_after`
-- event `checkout_cart_add_product_complete` -- this event only when normal add to cart
-  * withlist observer, marked to be deleted
-
-
-### *add to withlist* `wishlist/index/add`:
-- same buy request
-- cart candidates = type instance.processConfiguration -> `_prepareProduct`. Same as with add to cart.
-- create/update qty withlist item, just like quote item
-- event `wishlist_product_add_after`
-- event `wishlist_add_product`
-
-### *add to cart from wishlist* `withlist/index/cart`:
-
-Can override original buyRequest when adding to cart.
-NO event _checkout_cart_add_product_complete_.
-
-- load withlist item and options
-- merge buy request - saved and current.
-- wishlist item.addToCart
-- `cart.addProduct` with merged buyRequest:
-  * events `sales_quote_product_add_after`, `checkout_cart_product_add_after`
-- cart.save
-  * event `checkout_cart_save_before`
-  * event `checkout_cart_save_after`
-- quote.collectTotals
-- \Magento\Wishlist\Helper\Data::calculate
-  * write to customer session
-  * event `wishlist_items_renewed`
-
-### *merge quotes* controller `customer/account/loginPost`:
-
-Cart model is not used at all.
-
-- \Magento\Customer\Model\Session::setCustomerDataAsLoggedIn
-- event `customer_login`
-- \Magento\Checkout\Observer\LoadCustomerQuoteObserver
-- checkout session.`loadCustomerQuote`:
-  * event `load_customer_quote_before`
-  * finds existing customer quote
-  * detects that guest quote <> customer quote
-  * customer quote.`merge`(guest quote):
-    + event `sales_quote_merge_before`
-    + for each quote item.`compare` - product id, options same
-    + if items same, qty++
-    + if guest item is new, clone quote item, quote.addItem, event `sales_quote_add_item`
-    + event `sales_quote_merge_after`
-  * *delete guest quote*
-
-### *reorder* controller `sales/order/reorder`:
-
-Like normal add to cart, but NO event _checkout_cart_add_product_complete_.
-
-- load order, ensure can view
-- for each order item, `cart.addOrderItem` - converts order item to quote item:
-  * load product
-  * get item option buyRequest
-  * `cart.addProduct` with old buy request
-    + events `sales_quote_product_add_after`, `checkout_cart_product_add_after`
-
-
-## Describe how to customize the process of adding a product to the cart.
-- plugin over product type `prepareForCartAdvanced`
-- event `catalog_product_type_prepare_full_options` - custom options in `_prepareOptions`
-- plugin over \Magento\Quote\Model\Quote\Item\Processor::prepare - qty, custom price
-- event `checkout_cart_product_add_after`
-
-## Which different scenarios should you take into account?
-- add to cart from catalog
-- add to cart from wishlist
-- move all wishlist to cart
-- merge quote when existing customer has quote, then shops as a guest and logs in
-- admin create order
-- admin reorder
-- configure added product - change custom options
-
-
-## Render product types
-checkout cart index:
-- `<update handle="checkout_cart_item_renderers"/>`
-- `<update handle="checkout_item_price_renderers"/>`
-
-- block \Magento\Checkout\Block\Cart\AbstractCart::getItems - quote visible items
-  * can limit with *pagination*
-  * *custom_items* can override
-- abstract cart.`getItemHtml`(quote item)
-- render via abstract cart.`getItemRenderer` by product type
-  * renderer child block `renderer.list` \Magento\Framework\View\Element\RendererList
-  * renderer list block.getRenderer(type, template)
-  * finds child block by alias = product type
-  * \Magento\Checkout\Block\Cart\Item\Renderer
-  * 
-
-Customizations:
-- provide cart block data arguments `<referenceBlock name="checkout.cart.form">`:
-  * `renderer_list_name` - use custom renderer list
-  * `overriden_templates` - array by product type
-  * `renderer_template` - regardless of product type
-- in `checkout_cart_item_renderers`, `<referenceBlock name='renderer.list'>`, add child blocks by alias = product type. E.g.
-
-```xml
-<referenceBlock name="checkout.cart.item.renderers">
-    <block class="Magento\Checkout\Block\Cart\Item\Renderer" name="checkout.cart.item.renderers.default" as="default" template="Magento_Checkout::cart/item/default.phtml">
-        <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions" name="checkout.cart.item.renderers.default.actions" as="actions">
-            <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions\Edit" name="checkout.cart.item.renderers.default.actions.edit" template="Magento_Checkout::cart/item/renderer/actions/edit.phtml"/>
-            <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions\Remove" name="checkout.cart.item.renderers.default.actions.remove" template="Magento_Checkout::cart/item/renderer/actions/remove.phtml"/>
-        </block>
-    </block>
-</referenceBlock>
-```
-
-## Describe the available shopping cart operations.
-
-### Configure product in cart - controller `checkout/cart/configure`
-Product view and product configure are rendered via same helper
-\Magento\Catalog\Helper\Product\View.prepareAndRender.
-
-The only difference is params:
-- category_id - can be `false`
-- configure_mode - optional
-- buy_request - optional
-- specify_options - error message if missing options
-
-*Normal product view*:
-- params[category_id] = current
-- params[specify_options] - from product type
-- helper product view.prepareAndRender
-  * \Magento\Catalog\Helper\Product::initProduct - load product, check visible/enabled
-    + event `catalog_controller_product_init_before`
-    + event `catalog_controller_product_init_after`
-  * event `catalog_controller_product_view`
-
-*Configure product*:
-- params[`buyRequest`] = quote item.buyRequest
-- helper product view.prepareAndRender
-  * product helper.initProduct
-  * product helper.`prepareProductOptions` - set default selections from buy request, e.g. selected size=XXL
-    + product.processBuyRequest, `product type.processBuyRequest`, `product type.checkProductConfiguration`
-    + product.`setPreconfiguredValues`
-  * product.setConfigureMode -- used to show all hidden customization options instantly in edit mode
-  * event `catalog_controller_product_view`
-
-product.getPreconfiguredValues is later used:
-- default product qty = product.preconfigured values.qty
-- custom option values = product.preconfigured values.option_{$id}
-
-### How do you add a field to the shipping address?
-
-Quote address extends AbstractExtensibleModel, and so should implement `getCustomAttributesCodes()`
-to add custom attributes. Custom attributes should load and save automatically, assuming you added
-a column in migration and registered custom attribute in plugin (see below).
-
-Quote address custom attributes:
-* community \Magento\Quote\Model\Quote\Address\CustomAttributeList - empty, use plugin to add
-* EE \Magento\CustomerCustomAttributes\Model\Quote\Address\CustomAttributeList::getAttributes
-  + customer address attributes + customer attributes
-
-Alternatively, you can always register extension attribute and load/save it manually.
diff --git a/8. Customizing the Checkout Process/4. Demonstrate ability to customize shipping and pa yment methods.md b/8. Customizing the Checkout Process/4. Demonstrate ability to customize shipping and pa yment methods.md
deleted file mode 100644
index 0fe2ce9..0000000
--- a/8. Customizing the Checkout Process/4. Demonstrate ability to customize shipping and pa yment methods.md	
+++ /dev/null
@@ -1,294 +0,0 @@
-# Demonstrate ability to customize shipping and payment methods
-
-[Customize checkout](http://devdocs.magento.com/guides/v2.2/howdoi/checkout/checkout_overview.html)
-
-## Describe how to troubleshoot payment methods.
-
-Awesome Magento documentation - [Payment Provider Gateway](https://devdocs.magento.com/guides/v2.2/payments-integrations/bk-payments-integrations.html)
-
-Following is brief digest of official documentation.
-
-Magento 2 replaces abstract payment method that you would normally extend with payment adapter.
-Where there used to be protected methods for every aspect - validate, set data, authorize, invoice, refund etc. -
-now it moves to separate classes. Just like with controllers where each action resides in own class.
-All you need to do is wire your pieces together with DI config.
-
-Additional benefit - you can smoothly choose between simple class implementation or make a composite - split
-your business logic into even more fine grained pieces and mix them.
-
-Terms:
-- *payment adapter* - config-based payment method implementation. Holds operation pool, payment validator,
-  value handler, form block type, info block type.
-
-  [Model\Method\Adapter](https://github.com/magento/magento2/blob/2.2/app/code/Magento/Payment/Model/Method/Adapter.php)
-
-- *validator pool* - check country, currency, min-max amount etc. Magento 1 equivalent
-  is `method.isApplicableToQuote()`.
-
-  Fixed validator codes:
-  - `global` - called in `payment method.validate()`. Called by quote payment.importData
-    right after `payment method.assignData`.
-  - `availability` - called in `payment method.isAvailable()`
-  - `country` - called in `payment method.canUseForCountry()`
-  - `currency` - called in `payment method.canUseForCurrency()`
-
-  [Gateway\Validator\ValidatorInterface](https://github.com/magento/magento2/blob/2.2/app/code/Magento/Payment/Gateway/Validator/ValidatorInterface.php)
-
-- *value handler pool* - returns configuration params like `can_void`, `can_capture`. Holds multiple value handlers
-  by config param name and required handler `default`.
-
-  * [Gateway\Config\ValueHandlerPool](https://github.com/magento/magento2/blob/2.2/app/code/Magento/Payment/Gateway/Config/ValueHandlerPool.php)
-  * [Gateway\Config\ValueHandlerInterface](https://github.com/magento/magento2/blob/2.2/app/code/Magento/Payment/Gateway/Config/ValueHandlerInterface.php)
-
-- [*command pool*](https://devdocs.magento.com/guides/v2.2/payments-integrations/payment-gateway/command-pool.html) 
-  - holds commands.
-
-  [Gateway\Command\CommandPool](https://github.com/magento/magento2/blob/2.2/app/code/Magento/Payment/Gateway/Command/CommandPool.php)
-
-- [*gateway command*](https://devdocs.magento.com/guides/v2.2/payments-integrations/payment-gateway/gateway-command.html)
-  - authorize, sale, invoice, refund, cancel, void etc. Holds request builder, transfer factory, client,
-    operation validator, result processor.
-
-  Magento 1 analogs - `method.authorize()`, `method.capture()`, `method.refund()` etc.
-
-  [Gateway\CommandInterface](https://github.com/magento/magento2/blob/2.2/app/code/Magento/Payment/Gateway/CommandInterface.php)
-
-- [*request builder*](https://devdocs.magento.com/guides/v2.2/payments-integrations/payment-gateway/request-builder.html)
-  - given subject (quote, order or invoice) as array, prepares request parameters
-  as array - amounts, transaction ids, cart contents etc.
-
-  [Gateway\Request\BuilderInterface](https://github.com/magento/magento2/blob/2.2/app/code/Magento/Payment/Gateway/Request/BuilderInterface.php)
-
-- *transfer factory* - convert request parameters into transfer object. Here you add lowest level call params -
-  request method (get/post etc.), headers, API URL, encode body. Transfer object is built with transfer factory
-  builder, just like you use searchCriteriaBuilder to create searchCriteria.
-
-  [Gateway\Http\TransferFactoryInterface](https://github.com/magento/magento2/blob/2.2/app/code/Magento/Payment/Gateway/Http/TransferFactoryInterface.php)
-
-- [*gateway client*](https://devdocs.magento.com/guides/v2.2/payments-integrations/payment-gateway/gateway-client.html)
-  - simply makes a call with given parameters, e.g. sends Curl request. Don't reinvent
-  the wheel, you shouldn't need to implement this, just use default Zend and Soap clients,
-  you only need to format transfer object for them.
-
-  [Gateway\Http\ClientInterface](https://github.com/magento/magento2/blob/2.2/app/code/Magento/Payment/Gateway/Http/ClientInterface.php)
-
-- [*response validator*](https://devdocs.magento.com/guides/v2.2/payments-integrations/payment-gateway/response-validator.html)
-  - checks response - maybe HTTP response code, body, parse returned errors etc.
-
-  [Gateway\Validator\ResultInterface](https://github.com/magento/magento2/blob/2.2/app/code/Magento/Payment/Gateway/Validator/ResultInterface.php)
-
-- [*response handler*](https://devdocs.magento.com/guides/v2.2/payments-integrations/payment-gateway/response-handler.html)
-  - save response detauls in payment additional data, save transaction numbers, change
-  order status, send email etc.
-
-  [Gateway\Response\HandlerInterface](https://github.com/magento/magento2/blob/2.2/app/code/Magento/Payment/Gateway/Response/HandlerInterface.php)
-
-- *form block type* - payment form only in adminhtml.
-
-- *info block type* - payment info
-
-  * [Block\Info](https://github.com/magento/magento2/blob/2.2/app/code/Magento/Payment/Block/Info.php)
-    - like in M1, shows key-value strings, overwrite `_prepareSpecificInformation`.
-  * [Block\ConfigurableInfo](https://github.com/magento/magento2/blob/2.2/app/code/Magento/Payment/Block/ConfigurableInfo.php) - automatically shows values from payment.additional_information:
-    + config.xml payment method declaration - show `paymentInfoKeys` and exclude `privateInfoKeys` - comma separated.
-    + override `getLabel` to show human labels instead of raw field keys
-
-config.xml standard fields:
-- active
-- title
-- payment_action
-- can_initialize
-- can_use_internal
-- can_use_checkout
-- can_edit
-- is_gateway
-- is_offline
-- min_order_total
-- max_order_total
-- order_place_redirect_url
-- ...
-
-Gateway\ConfigInterface - reads scope config by pattern:
-- getValue(field, store) - scopeConfig.getValue(pathPattern + methodCode)
-- setMethodCode - used in getValue
-- setPathPattern - used in getValue
-
-
-## Passing user data from frontend checkout form to payment method:
-
-[Get payment information from frontend to backend](https://devdocs.magento.com/guides/v2.2/payments-integrations/base-integration/get-payment-info.html)
-
-- in JS method renderer implement `getData`. default fields `method` and `po_number`.
-  You can explicitly send `additional_data`, or all unknown keys will automatically be [moved](https://github.com/magento/magento2/blob/2.2/app/code/Magento/Quote/Model/Quote/Payment.php#L212)
-  into `additional_data` in backend.
-- \Magento\Checkout\Model\GuestPaymentInformationManagement::savePaymentInformationAndPlaceOrder
-- \Magento\Quote\Model\PaymentMethodManagement::set
-- quote payment.[importData](https://github.com/magento/magento2/blob/2.2/app/code/Magento/Quote/Model/Quote/Payment.php#L170)
-- event `sales_quote_payment_import_data_before`
-- `method instance.isAvailable`
-- method specification.isApplicable - checks one by one:
-  * can use checkout - `$paymentMethod->canUseCheckout`
-  * use for country - `$paymentMethod->canUseForCountry`
-  * use for currency - `$paymentMethod->canUseForCurrency`
-  * order total min max - between `$paymentMethod->getConfigData('min_order_total')` and `max_order_total`
-
-  [Model\Checks\SpecificationInterface](https://github.com/magento/magento2/blob/2.2/app/code/Magento/Payment/Model/Checks/SpecificationInterface.php)
-
-- `method instance.assignData`:
-  - event `payment_method_assign_data_{$code}`
-  - event `payment_method_assign_data`
-
-## Old Magento 1 payment flow
-1. get payment methods
-    - isAvailable, event `payment_method_is_active`
-    - method.isApplicableToQuote -- check country, currency, min-max, zero total
-2. save payment
-    - quote.payment.importData:
-      * event `sales_quote_payment_import_data_before`
-      * method.assignData
-      * method.validate
-    - quote payment._beforeSave
-      * method.prepareSave
-    - method.getCheckoutRedirectUrl
-
-### GET /V1/carts/mine/payment-information - get available methods
-- \Magento\Checkout\Model\PaymentInformationManagement::getPaymentInformation
-- \Magento\Quote\Model\PaymentMethodManagement::getList
-- \Magento\Payment\Model\MethodList::getAvailableMethods
-  * `method.isActive`
-  * `method.isAvailable`
-  * method specification.`isApplicable`
-
-### POST /V1/carts/mine/payment-information - click Place order button
-- \Magento\Checkout\Model\PaymentInformationManagement::savePaymentInformationAndPlaceOrder
-  * payment = method, po_number, additional_information
-- \Magento\Quote\Model\PaymentMethodManagement::set
-  * `method.setChecks` - checkout, country, currency, min-max
-  * quote payment.importData - method, po_number, additional_information
-    + event `sales_quote_payment_import_data_before`
-    + merge checks + additionalChecks -- can set via DI
-    + \Magento\Payment\Model\Checks\SpecificationFactory::create -- use DI to register new checks by code
-    + `method.isAvailable`
-    + method specification.isApplicable - checkout, country, currency, min-max + DI registered
-    + `method.assignData` -- assuming Payment Adapter class:
-      - event `payment_method_assign_data_{$code}`
-      - event `payment_method_assign_data`
-    + `method.validate` -- assuming Payment Adapter class:
-      - validator[`global`].validate
-
-## Facade - Payment Adapter
-- isActive - getConfiguredValue('active'):
-  * value handler pool[`active`].handle(['field'=>'active'])
-  * or value handler pool[`default`].handle(['field'=>'active'])
-- isAvailable
-  * isActive
-  * validatorPool[`availability`].validate
-  * event `payment_method_is_active` -- can override result, same as M1
-- assignData
-  * event `payment_method_assign_data_{$code}`
-  * event `payment_method_assign_data`
-- validate -- called after method.assignData in placeOrder
-  * validatorPool[`global`].validate
-- canUseForCountry
-  * validatorPool[`country`].validate
-  * called by method specification.isApplicable
-- canUseForCurrency
-  * validatorPool[`currency`].validate
-- canOrder, canAuthorize, canCapture, canCaptuerPartial, canCaptureOnce, canRefundPartialPerInvoice, canVoid,
-  canUseInternal, canUseCheckout, canEdit, canFetchTransactionInfo, canReviewPayment, isGateway, isOffline,
-  isInitializationNeeded:
-  * read from config `can_*`
-
-*Commands:*
-
-Commands are normally executed by `commandPool.get(name).execute()`. There's a strange opportunity to
-inject *command manager* - `commandExecutor` argument - that will run all commands instead.
-There's even a default command manager implementation - it contains command pool and runs then just the same.
-But this doesn't seem to be used.
-
-- fetchTransactionInfo() - `can_fetch_transaction_information`, `fetch_transaction_information` gateway command
-- initialize() - `can_initialize`, `initiailze` command
-- order() - `can_order`, `order` gateway command. same as authorize + capture = sale?
-- authorize() - `can_authorize`, `authorize` command
-- capture() - `can_capture`, `capture` command
-- refund() - `can_refund`, `refund` command
-- cancel() - `can_cancel`, `can_cancel` command
-- void() - `can_void`, `void` command
-- acceptPayment() - `can_accept_payment`, `accept_payment` command
-- denyPayment() - `can_deny_payment`, `deny_payment` command
-
-
-Two more special commands: `vault_authorize`, `vault_sale`, `vault_capture`
-
-
-braintree - BraintreeFacade = Model\Method\Adapter:
-- BraintreeValueHandlerPool: default, can_void, can_cancel
-- BraintreeCommandPool: authorize, sale, capture, settlement, vault_authorize, vault_sale, vault_capture, void, refund, cancel, deny_payment
-- BraintreeValidatorPool: country
-
-braintree_cc_vault - BraintreeCreditCardVaultFacade = Magento\Vault\Model\Method\Vault:
-- `vaultProvider` = BraintreeFacade. very important, all methods proxy to this
-- BraintreeVaultPaymentValueHandlerPool: default
-
-Magento\Vault\Model\Method\Vault:
-- pure class, no parent, interface \Magento\Vault\Model\VaultPaymentInterface
-- proxies almost all methods: is`*`, can`*`, validate
-- not implemented, throws error: initialize(), order(), refund(), cancel(), void(), acceptPayment(), denyPayment()
-- assignData:
-  * event `payment_method_assign_data_vault`
-  * event `payment_method_assign_data_vault_{$code}`
-  * original payment `method.assignData`
-- authorize:
-  * attach token extension attribute:
-    + `customer_id` from payment.additional_information
-    + `publish_hash` from payment.additional_information
-    + order payment.extension attributes[`vault_payment_token`] =
-    \Magento\Vault\Api\PaymentTokenManagementInterface::getByPublicHash(`publish_hash`, `customer_id`)
-    + select from `vault_payment_token` where publish_hash = ? and customer_id = ?/NULL
-  * commandManagerPool[`method.code`].executeBycode(`vault_authorize`)
-- capture:
-  * ONLY for `order`=`sale` payment action? Authorization transaction must not exist
-  * attach token extension attribute
-  * commandManagerPool[`method.code`].executeBycode(`vault_sale`)
-
-### Payment Tips
-
-Sometimes capture should do one of 3 things - sale, capture or vault_capture.
-Braintree makes CaptureStrategyCommand command that checks payment and
-calls needed capture type command.
-
-Virtual types can extend and augment each other pretty heavily, for example
-BraintreePayPalSaleCommand is based on BraintreePayPalAuthorizeCommand
-and changes only request builder.
-
-To make Vault work, after you receive normal payment, you save token by customer. Braintree
-does this in AuthorizationCommand handler chain in one of handlers. Token
-is simply read from response and put to order payment.extension_attributes[`vault_payment_token`].
-
-Vault on frontend:
-- in checkout config provider, finds all payment methods implementing Vault interface and returns codes for JS
-- in checkout payment methods, adds `vault` payment method group
-- get component providers \Magento\Vault\Model\Ui\TokenUiComponentProviderInterface - return params for JS component
-  * Braintree registers component in DI \Magento\Vault\Model\Ui\TokensConfigProvider
-- tokens = select from `vault_payment_token` where customer_id = ? and is_visible = 1 and is_active = 1 and expires_at > time
-- for each token, run component providers[method.code].getComponentForToken
-- window.checkoutConfig.payment.vault = [
-    `{$code}_{$i}` = componentConfig,
-    braintree_cc_vault_0 = {...},
-    braintree_cc_vault_1 = {...},
-  ]
-
-
-## What types of payment methods exist?
-- offline
-- online
-- gateway
-- vault - works over gateway, but executes different commands for authorize and capture. Always work in terms of previously saved token for customer.
-
-## What are the different payment flows?
-- isInitializationNeeded = true
-
-  Manually do the job in `initialize` and return custom order status and state.
-
-- authorize, capture
-- order = authorize + capture
diff --git a/8.Magento-Customising-The-Checkout-Process.md b/8.Magento-Customising-The-Checkout-Process.md
new file mode 100755
index 0000000..fdbc806
--- /dev/null
+++ b/8.Magento-Customising-The-Checkout-Process.md
@@ -0,0 +1,3125 @@
+8 - Customizing the Checkout Process
+====================================
+
+8.1 Demonstrate ability to use Quote, Quote Item, Address, and shopping Cart Price rules in checkout
+----------------------------------------------------------------------------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**Describe how to modify these models and effectively use them in customizations.**
+
+> Quote/Cart, Quote/Cart Items, Quote/Cart Addresses and Cart Price Rules are ALL their own entity which follow the [Service Contracts](#h.i0qq8aqgijv7) design pattern. Therefore the following ways of customisation are available:
+
+*   They all support [Extension Attributes](#h.2lcvcwr56aq)
+*   Quote/Cart Address supports [EAV Custom Attributes](#h.2lcvcwr56aq)
+*   Observable [Events dispatched](https://www.mageplaza.com/magento-2-module-development/magento-2-events.html&sa=D&ust=1609223265607000&usg=AOvVaw3hoe7G8p_gZJXAzywkihca) at certain points throughout each entity's checkout lifecycle.
+*   Implement / extend interfaces / class implementations via [DI Preference](#h.9ofwnl5q9fnf).
+*   [Plugin Interceptors](#h.nc1ow1wmf2km) around / before & after concrete class implementations of the interfaces (below).
+*   [JSComponent](#h.kg229a1fn1nm) & [Mixins](https://devdocs.magento.com/guides/v2.3/javascript-dev-guide/javascript/js_mixins.html%23example&sa=D&ust=1609223265609000&usg=AOvVaw2ZXvsf2EHlwrejlu7ciEyY)
+*   The following XML [Layout Handles](https://devdocs.magento.com/guides/v2.4/frontend-dev-guide/layouts/layout-overview.html%23layout-over-terms&sa=D&ust=1609223265609000&usg=AOvVaw0R1h3jI4LhzgqvneoVz4UF):
+
+    *   `checkout_cart_index.xml`
+    *   `checkout_index_index.xml`
+    *   `checkout_onepage_review.xml`
+    *   `checkout_onepage_success.xml`
+    *   `checkout_onepage_failure.xml`
+    *   `checkout_cart_item_renderers.xml`
+    *   `checkout_item_price_renderers.xml`
+    *   `checkout_cart_configure.xml`
+    *   `checkout_cart_configure_type_simple.xml`
+    *   `checkout_cart_sidebar_item_price_renderers.xml`
+    *   `checkout_onepage_review_item_renderers.xml`
+    *   `checkout_cart_sidebar_item_renderers.xml`
+    *   `checkout_cart_sidebar_total_renderers.xml`
+    *   `default.xml` (last resort)
+
+> The below sub-sections illustrate in detail the extendable functionality within each entity:
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Quote
+
+> Like all Modules, Magento_Quote uses the [Service Contracts](#h.i0qq8aqgijv7) design pattern to manage (C.R.U.D actions) Quotes/Carts with the following Repositories:
+>
+> The main interface for managing (C.R.U.D actions) Quotes/Carts:
+
+```php
+Magento\Quote\Api\CartRepositoryInterface::get(
+    $cartId
+);
+```
+
+> The main interface for managing (C.R.U.D actions) Quotes/Carts of Guests:
+
+```php
+Magento\Quote\Api\GuestCartRepositoryInterface::get(
+    $cartId
+);
+```
+
+> The main interface for placing quotes/carts i.e. createEmptyCart, assignCustomer, placeOrder actions:
+
+```php
+Magento\Quote\Api\CartManagementInterface::placeOrder(
+    $cartId,
+    \Magento\Quote\Api\Data\PaymentInterface $paymentMethod = null
+);
+```
+
+> The main interface for placing quotes/carts i.e. createEmptyCart, assignCustomer, placeOrder for Guests:
+
+```php
+Magento\Quote\Api\GuestCartManagementInterface::placeOrder(
+    $cartId,
+    \Magento\Quote\Api\Data\PaymentInterface $paymentMethod = null
+);
+```
+
+> Set shipping/billing methods and additional data for cart and collect totals:
+
+```php
+Magento\Quote\Api\CartTotalManagementInterface::collectTotals(
+    $cartId,
+    \Magento\Quote\Api\Data\PaymentInterface $paymentMethod,
+    $shippingCarrierCode = null,
+    $shippingMethodCode = null,
+    \Magento\Quote\Api\Data\TotalsAdditionalDataInterface $additionalData = null
+);
+```
+
+> Set shipping/billing methods and additional data for cart and collect totals of Guests:
+
+```php
+Magento\Quote\Api\GuestCartTotalManagementInterface::collectTotals(
+    $cartId,
+    \Magento\Quote\Api\Data\PaymentInterface $paymentMethod,
+    $shippingCarrierCode = null,
+    $shippingMethodCode = null,
+    \Magento\Quote\Api\Data\TotalsAdditionalDataInterface $additionalData = null
+);
+```
+
+> Returns Quote totals data for a specified Cart/Quote:
+
+```php
+Magento\Quote\Api\CartTotalRepositoryInterface::get(
+    $cartId
+);
+```
+
+> Returns Quote totals data for a specified Cart/Quote of a Guest:
+
+```php
+Magento\Quote\Api\GuestCartTotalRepositoryInterface::get(
+    $cartId
+);
+```
+
+> The main Quote/Cart data interface which houses all the quote properties such as `shipping_address`, `checkout_method`, items, `billing_address`, `entity_id` etc:
+
+```php
+Magento\Quote\Api\Data\CartInterface
+```
+
+> The data interface for calculating cart totals e.g. grand_total, subtotal, discount_amount, tax_amount etc:
+
+```php
+Magento\Quote\Api\Data\TotalsInterface
+```
+
+> Service checks if the user has ability to change the Quote:
+
+```php
+Magento\Quote\Api\ChangeQuoteControlInterface
+```
+
+> A data interface extension of `Magento\Framework\Api\SearchResultsInterface` used for searching Carts/Quotes in getList methods:
+
+```php
+Magento\Quote\Api\Data\CartSearchResultsInterface
+```
+
+> Data interface regarding currency information for this Cart/Quote:
+
+```php
+Magento\Quote\Api\Data\CurrencyInterface
+```
+
+| Table: **`quote`** | Notable Columns | Description |
+| --- | --- | --- |
+| Core Quote/Cart properties | `entity_id` int(10), `store_id`, smallint(5), `created_at`, timestamp, `updated_at`, timestamp, `is_active`, smallint(5), `is_virtual`, smallint(5), `is_multi_shipping`, smallint(5), `items_count`, int(10), `items_qty`, decimal(12,4), `store_to_base_rate`, decimal(12,4), `store_to_quote_rate`, decimal(12,4), `base_currency_code`, varchar(255), `store_currency_code`, varchar(255), `quote_currency_code`, varchar(255), `checkout_method`, varchar(255), `remote_ip`, varchar(45), `is_persistent`, smallint(5), `reserved_order_id`, varchar(64), `password_hash`, varchar(255), `global_currency_code`, varchar(255), `base_to_global_rate`, decimal(20,4), `base_to_quote_rate`, decimal(20,4), `trigger_recollect`, smallint(6) | `entity_id`: used all over the code and is the global identifier. **``is_active``**: Used for status / abandonment queries. Quotes are active when: Customer first creates a cart, it remains active even when logged out. Quotes are inactive when: Created by admin or API, a customer converts to an order Quotes are abandoned when: Quote/Cart is active but hasn't checked out for X length of time (configured in admin). **``is_virtual``**: Relating to [Virtual Products](#h.t3fkw0wf3trp) / [Downloadable Products](#h.614rvm49j6y9). **``is_multi_shipping``**: Used to indicate a [Multi-shipping](https://docs.magento.com/user-guide/configuration/sales/multishipping-settings.html&sa=D&ust=1609223265634000&usg=AOvVaw079SqVOaiMkuJU0G8bFd5G) Quote / Cart. |
+| Quote/Cart Totals Properties | `grand_total`, decimal(20,4), `base_grand_total`, decimal(20,4), subtotal, decimal(20,4), `base_subtotal`, decimal(20,4), `subtotal_with_discount`, decimal(20,4), `base_subtotal_with_discount`, decimal(20,4) | The Quotes / Cart's calculated totals. **`grand_total`**: The final price of the Quote/Cart. **`subtotal`**: Total of all Cart Items prices * by the Cart Item Qtys, before tax or discount. The difference between Base Totals & Totals are in the customer's Currency vs your shop's Base Currency. Used for the currency switcher. |
+| Quote/Cart Customer Properties | `customer_id`, int(10), `customer_tax_class_id`, int(10), `customer_group_id`, int(10), `customer_email`, varchar(255), `customer_prefix`, varchar(40), `customer_firstname`, varchar(255), `customer_middlename`, varchar(40), `customer_lastname`, varchar(255), `customer_suffix`, varchar(40), `customer_dob`, datetime, `customer_note`, varchar(255), `customer_note_notify`, smallint(5), `customer_is_guest`, smallint(5), `customer_taxvat`, varchar(255), `customer_gender`, varchar(255) | De-normalised / duplicate information data regarding the customer for a specific Quote/Cart. The reason why this information is duplicated is for preservation, in case the customer changes their information / remove's their account. It shouldn't affect Quotes / Sales going forward. Another reason is for read performance purposes, duplicating this data saves on extra relational queries. |
+| Sales / Cart Price Rules | `applied_rule_ids`, varchar(255), `coupon_code`, varchar(255) | Used for Sales / Cart Price Rules (promotions) applied Rule IDs / Coupons. |
+| [Magento Store Credit](https://docs.magento.com/user-guide/sales/store-credit.html&sa=D&ust=1609223265643000&usg=AOvVaw3HH3BN-FAWWASMN30lpOa5) (Magento commerce/enterprise only) | `customer_balance_amount_used`, decimal(20,4), `base_customer_bal_amount_used`, decimal(20,4), `use_customer_balance`, int(11) | These are all the relevant columns for [Magento Store Credit](https://docs.magento.com/user-guide/sales/store-credit.html&sa=D&ust=1609223265644000&usg=`AOvVaw230xRzowyrgC_QbpBaMwq7`) (Magento commerce/enterprise only). Store credit is an amount that is restored to a customer account. Customers can use their store credit to pay for purchases, and administrators can use store credit for cash refunds. Gift card balances can be credited to the customer's account, instead of using the gift card code for future purchases. |
+| [Magento Giftcard Accounts](https://docs.magento.com/user-guide/catalog/product-gift-card-accounts.html&sa=D&ust=1609223265645000&usg=AOvVaw0iq5JUqocV68hGgqxC2VON) (Magento commerce/enterprise only) | `gift_cards`, text, `gift_cards_amount`, decimal(20,4), `base_gift_cards_amount`, decimal(20,4), `gift_cards_amount_used`, decimal(20,4), `base_gift_cards_amount_used`, decimal(20,4) | A gift card account is automatically created for each Gift Card that is purchased. The value of the gift card can then be applied toward the purchase of a product in your store. You can also create gift card accounts from the Admin as a promotion or service for customers. The gift card account number corresponds to the gift card code. The value in the Quote/Cart table will be the amount being redeemed. |
+| [Magento Gift Options](https://docs.magento.com/user-guide/sales/gift-options.html&sa=D&ust=1609223265647000&usg=AOvVaw0VXkG9uh9mMhwyoLW2OUJc) | | `gift_message_id`, int(11) | **`gift_message_id`**: The foreign key linking `quote_item` to a [Gift Option](https://docs.magento.com/user-guide/sales/gift-options.html&sa=D&ust=1609223265648000&usg=AOvVaw23dQaBbWEvHYYH7KdQ4Gwv) |
+| [Magento Gift Wrapping](https://docs.magento.com/user-guide/sales/gift-wrap.html&sa=D&ust=1609223265649000&usg=AOvVaw17WaWQQQsKiRoUJqSvzC9G) (Magento commerce/enterprise only) | `gw_id`, int(11), `gw_allow_gift_receipt`, int(11), `gw_add_card`, int(11), `gw_base_price`, decimal(12,4), `gw_price`, decimal(12,4), `gw_items_base_price`, decimal(12,4), `gw_items_price`, decimal(12,4), `gw_card_base_price`, decimal(12,4), `gw_card_price`, decimal(12,4), `gw_base_tax_amount`, decimal(12,4), `gw_tax_amount`, decimal(12,4), `gw_items_base_tax_amount`, decimal(12,4), `gw_items_tax_amount`, decimal(12,4), `gw_card_base_tax_amount`, decimal(12,4), `gw_card_tax_amount`, decimal(12,4), `gw_base_price_incl_tax`, decimal(12,4), `gw_price_incl_tax`, decimal(12,4), `gw_items_base_price_incl_tax`, decimal(12,4), `gw_items_price_incl_tax`, decimal(12,4), `gw_card_base_price_incl_tax`, decimal(12,4), `gw_card_price_incl_tax`, decimal(12,4) | These are all the relevant columns for [Magento Gift Wrapping](https://docs.magento.com/user-guide/sales/gift-wrap.html&sa=D&ust=1609223265652000&usg=AOvVaw2JMyw5UtqnpvAZb7FoKfvS) (Magento commerce/enterprise only). Gift wrapping is available for any product that can be shipped, and can be offered for individual items or for the entire order. You can charge a separate price for each gift wrap design, and upload a thumbnail image of the design that appears as an option for the product in the cart. |
+| [Reward Points](https://docs.magento.com/user-guide/configuration/customers/reward-points.html&sa=D&ust=1609223265653000&usg=AOvVaw2859kqVzKhtA8GL4atV-jq) (Magento commerce/enterprise only) | `use_reward_points`, int(11), `reward_points_balance`, int(11), `base_reward_currency_amount`, decimal(20,4), `reward_currency_amount`, decimal(20,4) | These are all the relevant columns for [Reward Points](https://docs.magento.com/user-guide/configuration/customers/reward-points.html&sa=D&ust=1609223265655000&usg=AOvVaw3pILSmz7cdW7Ku2lPcI1k4) (Magento commerce/enterprise only) Or Loyalty Points. |
+| Unused columns | `ext_shipping_info`, text, `is_changed`, int(10), `orig_order_id`, int(10), `converted_at`, timestamp, `changed_flag`, int(10) | Though these are seemingly unused in the code, they might be here for backward compatibility with Magento 1 |
+
+
+![Magento Exam Information](./images/icon-info.png)The main thing to remember here is that Quotes adhere to the [Service Contracts](#h.i0qq8aqgijv7) design pattern, therefore all the necessary models for customisation are available within the Api/ directory of the Magento_Quote module. The main functions of these models to remember here are Managing Carts/Quotes, placing orders, assigning Shipping/Billing addresses, assigning Payments, assigning Shipping Methods, assigning Quote Items.
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Quote Item
+
+> Like all Modules, Magento_Quote uses the [Service Contracts](#h.i0qq8aqgijv7) design pattern to manage (C.R.U.D actions) Quote/Cart Items with the following Repositories:
+>
+> The main interface for managing Cart Items:
+
+
+```php
+Magento\Quote\Api\CartItemRepositoryInterface::save(
+    \Magento\Quote\Api\Data\CartItemInterface $cartItem
+);
+```
+
+> Manage that are assigned to a specified Guests cart:
+
+```php
+Magento\Quote\Api\GuestCartItemRepositoryInterface::save(
+    \Magento\Quote\Api\Data\CartItemInterface $cartItem
+);
+```
+
+> The main data interface for Cart/Quote items which houses properties such as `sku`, `qty`, `price`, `quote_id` etc:
+
+```php
+Magento\Quote\Api\Data\CartItemInterface
+```
+
+> The main data interface for calculating cart item totals e.g. `row_total`, `base_price`, `qty`, `tax_amount` etc:
+
+```php
+Magento\Quote\Api\Data\TotalsItemInterface
+```
+
+> Assigning Product Options ([Composite Product](#h.cbgifdse6zd5) Options) as an [Extension Attribute](#h.2lcvcwr56aq):
+
+```php
+Magento\Quote\Api\Data\ProductOptionInterface
+```
+
+> Data interface for additional totals (on other entities such as Address) which affect `grand_total` as an [Extension Attribute](#h.2lcvcwr56aq):
+
+```php
+Magento\Quote\Api\Data\TotalsAdditionalDataInterface
+```
+
+> Data interface for additional totals (on other entities such as Address) which affect `grand_total`:
+
+```php
+Magento\Quote\Api\Data\TotalSegmentInterface
+```
+
+|Table: **`quote_item`** | Notable Columns | Description |
+| --- | --- | --- |
+| Core Quote/Cart Item Properties | `item_id` - int(10) unsigned, `quote_id` - int(10) unsigned, `created_at` - timestamp, `updated_at` - timestamp, `product_id` - int(10) unsigned, `store_id` - smallint(5) unsigned, `parent_item_id` - int(10) unsigned, `is_virtual` - smallint(5) unsigned, `is_qty_decimal` - smallint(5) unsigned, qty - decimal(12,4), `free_shipping` - smallint(5) unsigned, `additional_data` - text, `item_id`: The main Quote/Cart Item Entity identifier | `quote_id`: The foreign key that links `quote_item` to quote table. `product_id`: The foreign key that links `quote_item` to (numerous) Product Entity tables. `parent_item_id`: If this item is an [Associated Simple Product](#h.98cgcmsgdbu5) then this is the identifier of the [Configurable Product](#h.98cgcmsgdbu5). `qty`: How many of this item is in the cart. `is_virtual`: Is this item a [Virtual Product](#h.t3fkw0wf3trp). `free_shipping`: Whether this Quote/Cart item is subject to free shipping. `additional_data`: JSON object for anything additional used for 3rd party modules.
+| Core Quote/Cart Item Product Data | sku - varchar(255), name - varchar(255), description - text, weight - decimal(12,4), `row_weight` - decimal(12,4), `product_type` - varchar(255), price - decimal(12,4), `redirect_url` - varchar(255), De-normalised / duplicate information data regarding the customer for a specific Quote/Cart. | The reason why this information is duplicated is for preservation, in case the Product changes or is removed - there is always a record of what was purchased. Another reason is for read performance purposes, duplicating this data saves on extra relational queries. `row_weight`: weight * qty. `price`: initial item price, declared during product association at the time that the item was added to the Quote/Cart.
+| Quote / Cart Item Totals | `base_price` - decimal(12,4), `custom_price` - decimal(12,4), `original_custom_price` - decimal(12,4), `base_cost` - decimal(12,4), `discount_percent` - decimal(12,4), `discount_amount` - decimal(20,4), `base_discount_amount` - decimal(20,4), `base_tax_amount` - decimal(20,4), `row_total` - decimal(20,4), `base_row_total` - decimal(20,4), `row_total_with_discount` - decimal(20,4), `price_incl_tax` - decimal(20,4), `base_price_incl_tax` - decimal(20,4), `row_total_incl_tax` - decimal(20,4), `base_row_total_incl_tax` - decimal(20,4), The difference between Base Prices & Prices are in the customer's Currency vs your shop's Base Currency. Used for the currency switcher. For example: | `row_total`: The Grand total for this item of this row (qty + discount + tax + price) in the customer's chosen currency. `base_row_total`: The Grand total for this item of this row (qty + discount + tax + price) in your store's chosen base currency. `custom_price`: A new price that can be declared and recalculated during the calculation process. `original_custom_price`: Original defined value of custom price without any conversion
+| Quote / Cart Item Tax Amounts | `tax_percent` - decimal(12,4), `tax_amount` - decimal(20,4), `base_tax_before_discount` - decimal(20,4), `tax_before_discount` - decimal(20,4), `weee_tax_applied` - text, `weee_tax_applied_amount` - decimal(12,4), `weee_tax_applied_row_amount` - decimal(12,4), `weee_tax_disposition` - decimal(12,4), `weee_tax_row_disposition` - decimal(12,4), `base_weee_tax_applied_amount` - decimal(12,4), `base_weee_tax_applied_row_amnt` - decimal(12,4), `base_weee_tax_disposition` - decimal(12,4), `base_weee_tax_row_disposition` - decimal(12,4), `discount_tax_compensation_amount` - decimal(20,4), `base_discount_tax_compensation_amount` - decimal(20,4), The [`Magento_Weee`](https://devdocs.magento.com/guides/v2.3/mrg/ce/Weee.html&sa=D&ust=1609223265677000&usg=`AOvVaw0B_HdWyEbZDhpU4flweObr`) module enables the application of fees/fixed product taxes (FPT) on certain types of products, usually related to electronic devices and recycling. Fixed product taxes can be used to set up a WEEE tax that is a fixed amount, rather than a percentage of the product price. FPT can be configured to be displayed at various places in Magento. Rules, amounts, and display options can be configured in the backend. This module extends the existing functionality of `Magento_Tax`. | `tax_amount`: Total tax of this Quote/Cart item including qty for this row. `discount_tax_compensation_amount`: Row `tax_amount` - row `tax_amount` after discount.
+| [Magento Gift Options](https://docs.magento.com/user-guide/sales/gift-options.html&sa=D&ust=1609223265678000&usg=`AOvVaw17bpkriufBse_w0GC122k1`) | `gift_message_id` - int(11) | `gift_message_id`: The foreign key linking `quote_item` to a [Gift Option](https://docs.magento.com/user-guide/sales/gift-options.html&sa=D&ust=1609223265679000&usg=AOvVaw0ddGxSfRtNEfZ4by7-wB11) |
+| [Magento Gift Wrapping](https://docs.magento.com/user-guide/sales/gift-wrap.html&sa=D&ust=1609223265680000&usg=AOvVaw0Rgwl3nyJ8maPW3LfdeUFo) (Magento commerce/enterprise only) | `gw_id` - int(11), `gw_base_price` - decimal(12,4), `gw_price` - decimal(12,4), `gw_base_tax_amount` - decimal(12,4), `gw_tax_amount` - decimal(12,4) | These are all the relevant columns for [Magento Gift Wrapping](https://docs.magento.com/user-guide/sales/gift-wrap.html&sa=D&ust=1609223265682000&usg=`AOvVaw0LqqLOQTxyh8PiSlV_OMfN`) (Magento commerce/enterprise only). Gift wrapping is available for any product that can be shipped, and can be offered for individual items or for the entire order. You can charge a separate price for each gift wrap design, and upload a thumbnail image of the design that appears as an option for the product in the cart. |
+| [Magento Events](https://docs.magento.com/user-guide/marketing/event-create.html&sa=D&ust=1609223265682000&usg=AOvVaw1ZnfLcebV0Cebi7RdxWd-Z) (Magento commerce/enterprise only) | `event_id` - int(11) | [`Magento_CatalogEvent`](https://docs.magento.com/user-guide/marketing/event-create.html&sa=D&ust=1609223265684000&usg=AOvVaw0loMrqR-bwM68fqI3okHay) module is designed for creating campaigns that encourage customers to buy products with lower prices. There are three types of the catalog events: upcoming, open, closed. |
+| [Magento Gift Registries](https://docs.magento.com/user-guide/marketing/gift-registries.html&sa=D&ust=1609223265684000&usg=`AOvVaw3t16tNCRCcriXVFUHMH_UZ`) (Magento commerce/enterprise only) | `giftregistry_item_id` - int(11) | [`Magento_GiftRegistry`](https://docs.magento.com/user-guide/marketing/gift-registries.html&sa=D&ust=1609223265686000&usg=AOvVaw2SjrY-`R_Xbr1UfG5YjdpuM`) gives your customers the ability to create gift registries for special occasions, and to invite their friends and family to purchase their gifts from the gift registry. Magento keeps track of all items purchased and the quantities remaining. |
+| Sales / Cart Price Rules | `applied_rule_ids` - text, `no_discount` - smallint(5) unsigned | Used for Sales / Cart Price Rules (promotions) applied Rule IDs / Coupons. `no_discount`: Yes/No to applying Sales Rules on this item. |
+
+
+![Magento Exam Information](./images/icon-info.png)The main thing to remember here is that Quote Items adhere to the [Service Contracts](#h.i0qq8aqgijv7) design pattern, therefore all the necessary models for customisation are available within the Api/ directory of the Magento_Quote module. The main functions of these models to remember here are Managing Carts/Quote Items, assigning an item to a Quote, assigning properties of an item such as row_total, qty etc, applying additional totals to a Cart/Quote Item. Separate management interfaces exist for both logged in Customers & Guests.
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Payments
+
+> Like all Modules, Magento_Quote uses the [Service Contracts](#h.i0qq8aqgijv7) design pattern to manage (C.R.U.D actions) Payments with the following Repositories:
+>
+> The main interface for managing specified payment methods to a specified shopping cart:
+
+```php
+Magento\Quote\Api\PaymentMethodManagementInterface::set(
+    $cartId,
+    \Magento\Quote\Api\Data\PaymentInterface
+    $method
+);
+```
+
+> The main interface for managing specified payment methods to a specified shopping cart of a Guest:
+
+```php
+Magento\Quote\Api\GuestPaymentMethodManagementInterface::set(
+    $cartId,
+    \Magento\Quote\Api\Data\PaymentInterface
+    $method
+);
+```
+
+> The main data interface for Payments housing properties such as method, `po_number`, `additional_data`:
+
+```php
+Magento\Quote\Api\Data\PaymentInterface
+```
+
+> The main data interface for Payments Method housing properties such as title & code:
+
+```php
+Magento\Quote\Api\Data\PaymentMethodInterface
+```
+
+| Database Table: **`quote_payment`** | Notable Columns | Description |
+| --- | --- | --- |
+| Core Quote Payment Properties | `payment_id` - int(10) unsigned, `quote_id` - int(10) unsigned, `created_at` - timestamp, `updated_at` - timestamp, method - varchar(255), `po_number` - varchar(255), `additional_data` - text, `additional_information` - text. | `payment_id`: The main Quote/Cart Item Entity identifier. `quote_id`: The foreign key that links `quote_item` to quote table. method: This is the Payment Method code used to checkout .e.g "braintree". `po_number`: Purchase Order number, for Purchase Order Payment Methods. `additional_data`: Magento uses this to input quote related data once the customer submits the payment form. `additional_information`: This can be used to place 3rd party module information. Braintree for example adds "`payment_method_nonce`". |
+| Quote Payment Credit Card Information | `cc_type` - varchar(255), `cc_number_enc` - varchar(255), `cc_last_4` - varchar(255), `cc_cid_enc` - varchar(255), `cc_owner` - varchar(255), `cc_exp_month` - varchar(255), `cc_exp_year` - smallint(5) unsigned, `cc_ss_owner` - varchar(255), `cc_ss_start_month` - smallint(5) unsigned, `cc_ss_start_year` - smallint(5) unsigned, `cc_ss_issue` - varchar(255) | The non-sensitive card information. In order to store the sensitive information you would have to be PCI Compliant, Magneto Cloud by default has PCI Compliant infrastructure, but Magento Community is not necessarily. |
+| Quote Payment PayPal Properties | `paypal_payer_id` - varchar(255), `paypal_payer_status` - varchar(255), `paypal_correlation_id` - varchar(255) | PayPal relational information. |
+
+![Magento Exam Information](./images/icon-info.png)The main thing to remember here is that Payments adhere to the [Service Contracts](#h.i0qq8aqgijv7) design pattern, therefore all the necessary models for customisation are available within the Api/ directory of the Magento_Quote module. The main functions of these models to remember here are Managing Payments (C.R.U.D actions), assigning a Payment to a Quote, assigning properties of a Payment such as code, title, method etc. Separate management interfaces exist for both logged in Customers & Guests.
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Shipping Methods
+
+> Like all Modules, Magento_Quote uses the [Service Contracts](#h.i0qq8aqgijv7) design pattern to manage (C.R.U.D actions) Shipping Methods with the following Repositories:
+>
+> Estimate shipping by address and return list of available shipping methods:
+
+```php
+Magento\Quote\Api\ShipmentEstimationInterface::estimateByExtendedAddress(
+    $cartId,
+    \Magento\Quote\Api\Data\AddressInterface $address
+);
+```
+
+> Estimate shipping by address and return list of available shipping methods for Guest:
+
+```php
+Magento\Quote\Api\GuestShipmentEstimationInterface::estimateByExtendedAddress(
+    $cartId,
+    \Magento\Quote\Api\Data\AddressInterface $address
+);
+```
+
+> Estimate shipping by Shipping Address:
+
+```php
+Magento\Quote\Api\ShippingMethodManagementInterface::estimateByAddress(
+    $cartId,
+    \Magento\Quote\Api\Data\EstimateAddressInterface $address
+);
+```
+
+> Estimate shipping by Shipping Address for Guests:
+
+```php
+Magento\Quote\Api\GuestShippingMethodManagementInterface::estimateByAddress(
+    $cartId,
+    \Magento\Quote\Api\Data\EstimateAddressInterface $address
+);
+```
+
+> The main data interface for managing shipments in Quotes:
+
+```php
+Magento\Quote\Api\Data\ShippingInterface
+```
+
+> A data interface for creating an address for estimation with properties such as `country_id`, `region_id`, `postcode` etc:
+
+```php
+Magento\Quote\Api\Data\EstimateAddressInterface
+```
+
+> A data interface for assigning shipping methods to Quotes/Cart:
+
+```php
+Magento\Quote\Api\Data\ShippingAssignmentInterface::public function setItems(
+    \Magento\Quote\Api\Data\CartItemInterface[] $value
+);
+```
+
+> The data interface for creating new Shipping Methods with properties such as `carrier_code`, `method_code`, `carrier_title`, `method_title` etc:
+
+```php
+Magento\Quote\Api\Data\ShippingMethodInterface
+```
+
+| Database Table: **`quote_shipping_rate`** | Notable Columns | Description |
+| --- | --- | --- |
+| Quote/Cart Shipping Rates Core Properties | `rate_id` - int(10) unsigned, `address_id` - int(10) unsigned, `created_at` - timestamp, `updated_at` - timestamp, code - varchar(255), method - varchar(255), `method_title` - text, `method_description` - text, `error_message` - text | `rate_id`: The main Quote/Cart Item Entity identifier. `address_id`: The foreign key that links `quote_shipping_rate` to `quote_address` table. method: This is the Shipping Rate Method Code, often duplicated in other tables such as `shipping_method` column of `quote_address` (below) as an alternate human-friendly identifier. code: This is the more specific Shipping Rate method (above) for dynamic rates (such as [Table Rates](https://docs.magento.com/user-guide/shipping/shipping-table-rate.html&sa=D&ust=1609223265713000&usg=AOvVaw3EIc7rGRjXihlyWhv02loG)) whereby the method = tablerate code would be bestway (default) delimited via an underscore (`tablerate_bestway`) which would translate to: Use the Table Rates Best Method Available. Whatever is "Best" depends on the calculation [Conditions](https://docs.magento.com/user-guide/shipping/shipping-table-rate.html%23step-1-complete-the-default-settings&sa=D&ust=1609223265713000&usg=`AOvVaw0EybmPIuVVUVn1vzORbV_t`) & the [Uploaded Rates CSV](https://docs.magento.com/user-guide/shipping/shipping-table-rate.html%23step-3-import-the-table-rate-data&sa=D&ust=1609223265713000&usg=AOvVaw2rwYJG7VYdcMTsPIGM0kjq) price for that postcode. `method_title`: The headline of this Cart/Quote Shipping Rate displayed to the customer. Correlating to the main method name e.g. "Standard" (defined in admin). `error_message`: Exceptions encountered whilst calculating shipping rates. |
+| Quote/Cart Shipping Rates Totals Properties | `price` - decimal(20,4) | `price`: The Grand Total of the cost for this shipping method posting to this Quote/Cart Address |
+| Quote/Cart Shipping Rates [Carrier](https://docs.magento.com/user-guide/shipping/carriers.html&sa=D&ust=1609223265715000&usg=AOvVaw3jHUsd99DklWfi6Dc1VDlu) Properties | carrier - varchar(255), `carrier_title` - varchar(255), `carrier_type` - text, `carrier_id` - text, `carriergroup_id` - text, carriergroup - text, `carriergroup_shipping_details` - text | Relational columns regarding [Magento Shipping Carriers](https://docs.magento.com/user-guide/shipping/carriers.html&sa=D&ust=1609223265717000&usg=AOvVaw2wcibpDuMsxpFaZ6NX4ym1). If you have a commercial account with a supported carrier, you can offer your customers the convenience of choosing that carrier during checkout. The rates are automatically downloaded, so you do not need to look up the information. |
+
+
+![Magento Exam Information](./images/icon-info.png)The main thing to remember here is that Shipping Methods adhere to the [Service Contracts](#h.i0qq8aqgijv7) design pattern, therefore all the necessary models for customisation are available within the Api/ directory of the Magento_Quote module. The main functions of these models to remember here are Managing Shipping Methods (C.R.U.D actions), assigning a Shipping Methods to a Quote, assigning properties of a Shipping Method such as country_id, region_id, postcode etc. Separate management interfaces exist for both logged in Customers & Guests.
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Addresses
+
+> Like all Modules, Magento_SalesRule uses the [Service Contracts](#h.i0qq8aqgijv7) design pattern to manage (C.R.U.D actions) Cart Price Rules with the following Repositories:
+>
+> Assigns a specified billing address to a specified cart:
+
+```php
+Magento\Quote\Api\BillingAddressManagementInterface::assign(
+    Magento\Quote\Api\Data\AddressInterface $address,
+    $useForShipping = false
+);
+```
+
+> Assign a specified billing address to a specified cart for Guests:
+
+```php
+Magento\Quote\Api\GuestBillingAddressManagementInterface::assign(
+    $cartId, \Magento\Quote\Api\Data\AddressInterface $address, $useForShipping = false
+);
+```
+
+> The main Api data interface for Shipping & Billing Addresses which houses properties such as `email`, `region_code`, `customer_id`, `street`, `telephone`, `postcode`, `city`, `firstname`, `lastname` etc:
+
+```php
+Magento\Quote\Api\Data\AddressInterface
+```
+
+> Retrieve existing Address Additional Data as [Extension Attributes](#h.2lcvcwr56aq) object or create a new one. Address Additional Data are custom additional fields in the format of a [Custom Attribute](#h.2lcvcwr56aq)
+
+```php
+Magento\Quote\Api\Data\AddressAdditionalDataInterface
+```
+
+| Database Table: **`quote_address`** | Notable Columns | Description |
+| --- | --- | --- |
+| Core Quote/Cart Address Properties | `address_id` - int(10) unsigned, `quote_id` - int(10) unsigned, `created_at` - timestamp, `updated_at` - timestamp, `customer_id` - int(10) unsigned, `save_in_address_book` - smallint(6), `customer_address_id` - int(10) unsigned, `address_type` - varchar(10), `same_as_billing` - smallint(5) unsigned, `customer_notes` - text, `collect_shipping_rates` - smallint(5) unsigned, `shipping_method` - varchar(120), `shipping_description` - varchar(255), `validated_country_code` - text, `validated_vat_number` - text, `free_shipping` - smallint(5) unsigned, `address_id`: The main Quote/Cart Address Entity Identifier | `quote_id`: The foreign key that links `quote_address` to quote table. `customer_id`: The foreign key that links `quote_address` to `customer_entity` table. `save_in_address_book`: Selected by the Customer, if ticked then this address will be tied to their account for future use. `address_type`: The column to differentiate between a Billing Address and a Shipping Address `same_as_billing`: Yes/No value to denote whether this Shipping address matches Billing (saves on duplicating data). `shipping_method`: This is the same value as the Shipping Method method column that was used to calculate the shipping amounts (e.g. `flatrate_flatrate`). |
+| Customer Quote/Cart Address Properties | email - varchar(255), prefix - varchar(40), firstname - varchar(255), middlename - varchar(40), lastname - varchar(255), suffix - varchar(40), company - varchar(255), street - varchar(255), city - varchar(255), region - varchar(255), `region_id` - int(10) unsigned, postcode - varchar(20), `country_id` - varchar(30), telephone - varchar(255), fax - varchar(255), De-normalised / duplicate information data regarding the customer for a specific Quote/Cart Address. | The reason why this information is duplicated is for preservation, in case the customer changes their information / remove's their account. It shouldn't affect Quotes / Sales going forward. Another reason is for read performance purposes, duplicating this data saves on extra relational queries. |
+| Quote/Cart Address Total Properties | weight - decimal(12,4), subtotal - decimal(20,4), `base_subtotal` - decimal(20,4), `subtotal_with_discount` - decimal(20,4), `base_subtotal_with_discount` - decimal(20,4), `tax_amount` - decimal(20,4), `base_tax_amount` - decimal(20,4), `shipping_amount` - decimal(20,4), `base_shipping_amount` - decimal(20,4), `shipping_tax_amount` - decimal(20,4), `base_shipping_tax_amount` - decimal(20,4), `discount_amount` - decimal(20,4), `base_discount_amount` - decimal(20,4), `grand_total` - decimal(20,4), `base_grand_total` - decimal(20,4), `applied_taxes` - text, `discount_description` - varchar(255), `shipping_discount_amount` - decimal(20,4), `base_shipping_discount_amount` - decimal(20,4), `subtotal_incl_tax` - decimal(20,4), `base_subtotal_total_incl_tax` - decimal(20,4), `discount_tax_compensation_amount` - decimal(20,4), `base_discount_tax_compensation_amount` - decimal(20,4), `shipping_discount_tax_compensation_amount` - decimal(20,4), `base_shipping_discount_tax_compensation_amnt` - decimal(20,4), `shipping_incl_tax` - decimal(20,4), `base_shipping_incl_tax` - decimal(20,4) | These totals are used to calculate [Magento Shipping Method Rates](https://docs.magento.com/user-guide/configuration/sales/delivery-methods.html&sa=D&ust=1609223265734000&usg=AOvVaw1NUzphzbyg0JQTbKPwlhcs). The difference between Base Amounts & Amounts are in the customer's Currency vs your shop's Base Currency. Used for the currency switcher. `grand_total`: This would be the final price of shipping for this Quote/Cart Address. `subtotal`: Total shipping amount for Quote/Cart Address, before tax or discount. `applied_taxes`: JSON encoded string containing the Tax rates for that specific store. For example: `{"GST":{"amount":1,"base_amount":1,"percent":10,"id":"GST","rates":[{"percent":10,"code":"GST","title":"GST"}],"item_id":"197836","item_type":"product","associated_item_id":null,"process":0}}`. `weight`: Important unit for calculating Table Rates. |
+| Quote/Cart Value Added Tax (VAT) | `vat_id` - text, `vat_is_valid` - smallint(6), `vat_request_id` - text, `vat_request_date` - text, `vat_request_success` - smallint(6) | Relational columns regarding [Magento Value Added Tax](https://docs.magento.com/user-guide/tax/vat.html&sa=D&ust=1609223265738000&usg=AOvVaw0tuZRour2aWSNh6GSYrQyQ). Some countries charge a value-added tax, or VAT, on goods and services. There can be different VAT rates depending on which stage you as a merchant are at in the manufacture or distribution of the products, materials, or services that you sell to your customers. In some cases, you might need to use more than one VAT rate in your store for tax calculation purposes. |
+| [Magento Giftcard Accounts](https://docs.magento.com/user-guide/catalog/product-gift-card-accounts.html&sa=D&ust=1609223265739000&usg=AOvVaw0A2kNf2NOi59-aZCYMXNQ1) (Magento commerce/enterprise only) | `gift_cards_amount` - decimal(20,4), `base_gift_cards_amount` - decimal(20,4), `gift_cards` - text, `used_gift_cards` - text, A gift card account is automatically created for each Gift Card that is purchased. The value of the gift card can then be applied toward the purchase of a product in your store. You can also create gift card accounts from the Admin as a promotion or service for customers. The gift card account number corresponds to the gift card code. The value in the Quote/Cart Address table will be the amount being redeemed. |
+| [Magento Gift Options](https://docs.magento.com/user-guide/sales/gift-options.html&sa=D&ust=1609223265740000&usg=AOvVaw2mROQ8OQIvT4KsGKFUN-Q8) | `gift_message_id` - int(11) | `gift_message_id`: The foreign key linking `quote_item` to a [Gift Option](https://docs.magento.com/user-guide/sales/gift-options.html&sa=D&ust=1609223265741000&usg=`AOvVaw1ZRX0m_UhtWPhE8OimlPqP`) |
+| [Magento Gift Wrapping](https://docs.magento.com/user-guide/sales/gift-wrap.html&sa=D&ust=1609223265742000&usg=`AOvVaw3haaTEXdIMiLKNqI_NL_67`) (Magento commerce/enterprise only) | `gw_id` - int(11), `gw_allow_gift_receipt` - int(11), `gw_add_card` - int(11), `gw_base_price` - decimal(12,4), `gw_price` - decimal(12,4), `gw_items_base_price` - decimal(12,4), `gw_items_price` - decimal(12,4), `gw_card_base_price` - decimal(12,4), `gw_card_price` - decimal(12,4), `gw_base_tax_amount` - decimal(12,4), `gw_tax_amount` - decimal(12,4), `gw_items_base_tax_amount` - decimal(12,4), `gw_items_tax_amount` - decimal(12,4), `gw_card_base_tax_amount` - decimal(12,4), `gw_card_tax_amount` - decimal(12,4), `gw_base_price_incl_tax` - decimal(12,4), `gw_price_incl_tax` - decimal(12,4), `gw_items_base_price_incl_tax` - decimal(12,4), `gw_items_price_incl_tax` - decimal(12,4), `gw_card_base_price_incl_tax` - decimal(12,4), `gw_card_price_incl_tax` - decimal(12,4) | These are all the relevant columns for [Magento Gift Wrapping](https://docs.magento.com/user-guide/sales/gift-wrap.html&sa=D&ust=1609223265747000&usg=`AOvVaw05zayxAmTy04HEoqQ4hCa_`) (Magento commerce/enterprise only). Gift wrapping is available for any product that can be shipped, and can be offered for individual items or for the entire order. You can charge a separate price for each gift wrap design, and upload a thumbnail image of the design that appears as an option for the product in the cart. |
+| | `giftregistry_item_id` - int(11) | |
+| [Magento Rewards & Loyalty](https://docs.magento.com/user-guide/marketing/rewards-loyalty.html&sa=D&ust=1609223265749000&usg=AOvVaw2VRBWm3Vs-r9onTmO2W0PU) (Magento commerce/enterprise only) | `base_customer_balance_amount` - decimal(20,4), `customer_balance_amount` - decimal(20,4), `reward_points_balance` - int(11), `base_reward_currency_amount` - decimal(20,4), `reward_currency_amount` - decimal(20,4) | Specifies the number of [](https://docs.magento.com/user-guide/marketing/rewards-loyalty.html&sa=D&ust=1609223265751000&usg=AOvVaw1VO2MeM-`Dvg3WzSE1fA1_4`) [reward points](https://docs.magento.com/user-guide/marketing/rewards-loyalty.html&sa=D&ust=1609223265751000&usg=AOvVaw1VO2MeM-`Dvg3WzSE1fA1_4`) that are earned by the customer. |
+
+
+![Magento Exam Information](./images/icon-info.png)The main thing to remember here is that Addresses adhere to the [Service Contracts](#h.i0qq8aqgijv7) design pattern, therefore all the necessary models for customisation are available within the Api/ directory of the Magento_Quote module. The main functions of these models to remember here are Addresses (C.R.U.D actions), assigning a Shipping Method to a Quote, assigning properties of a Shipping Method such as email, region_code, street, postcode, city etc. Separate management interfaces exist for both logged in Customers & Guests. Separate management interfaces exist for both logged in Shipping & Billing Addresses as well.
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Cart Price Rules
+
+> Please refer to the Sales / [Cart Price Rules](#h.9it0avmbiyyv) section.
+
+![Magento Exam Question](./images/icon-question.png)**Describe how to customize the process of adding a product to the cart.**
+
+> [Plugin Interceptors](#h.nc1ow1wmf2km) over the following classes:
+
+```php
+Magento\Catalog\Model\Product\Type\AbstractType::prepareForCartAdvanced(
+    Magento\Framework\DataObject $buyRequest,
+    \Magento\Catalog\Model\Product $product,
+    $processMode = null
+)
+```
+
+```php
+\Magento\Quote\Model\Quote\Item\Processor::prepare(
+    \Magento\Quote\Model\Quote\Item $item,
+    Magento\Framework\DataObject $request,
+    \Magento\Catalog\Model\Product $candidate
+)
+```
+
+> Observable [Events dispatched](https://www.mageplaza.com/magento-2-module-development/magento-2-events.html&sa=D&ust=1609223265755000&usg=AOvVaw0F1AxJ-CkGCsqQo2WEJBp7) on add-to-cart events:
+
+1.  `checkout_cart_product_add_after`
+2.  `checkout_cart_add_product_complete`
+3.  `checkout_cart_update_item_complete`
+4.  `checkout_cart_product_add_after`
+5.  `checkout_cart_update_items_before`
+6.  `checkout_cart_update_items_after`
+7.  `checkout_cart_save_before`
+8.  `checkout_cart_save_after`
+9.  `checkout_cart_product_update_after`
+10.  `catalog_product_type_prepare_full_options` ([Composite Product](#h.cbgifdse6zd5) Custom Options in `_prepareOptions` method).
+
+> A [JSComponent](#h.kg229a1fn1nm) [Mixin](https://magento.stackexchange.com/a/210392/24588&sa=D&ust=1609223265757000&usg=AOvVaw1RLUWzBlhxoOhGsOkaWIkr) on add-to-cart:
+
+`requirejs - config.js`
+```js
+var config = {
+    config: {
+        mixins: {
+            'Magento_Catalog/js/catalog-add-to-cart': {
+                'Custom_Module/js/catalog-add-to-cart-mixin': true
+            },
+        }
+    }
+};
+```
+
+`catalog-add-to-cart-mixin.js`
+```js
+define([
+    'jquery',
+    'mage/translate',
+    'jquery/ui',
+], function ($, $t, alert) {
+
+    'use strict';
+
+    return function (widget) {
+
+        console.log('catalog-add-to-cart-mixin');
+        $.widget('mage.catalogAddToCart', widget, {
+
+        });
+
+        return $.mage.catalogAddToCart;
+    }
+});
+```
+
+![Magento Exam Information](./images/icon-info.png)Remember the exam is multiple choice here, you won't be expected to memorise these events. Just know that Observables, Plugins & JsComponents are available to use at the point of adding to cart.
+
+![Magento Exam Question](./images/icon-question.png)**Which different scenarios should you take into account?**
+
+> When customising the add-to-cart process the following areas should be taken into account:
+
+1.  Add to cart from catalog
+2.  Add to cart from wishlist
+3.  Move all wishlist to cart
+4.  Merge quote when existing customer has quote, then shops as a guest and logs in
+5.  Admin create order
+6.  Admin reorder
+7.  Configure added product - change custom options
+
+8.2 Demonstrate ability to use totals models
+--------------------------------------------
+
+> `<module_dir>/etc/sales.xml` contains all kinds of total objects like `discount`, `subtotal`, `grand_total`, tax etc which display on cart pages or order details pages within all areas (`frontend`, `backend`).
+>
+> You can add custom total objects as well using this file. Check below link for more details. Custom totals can be used to add an additional tax or discount in Magento Checkout or modify the existing ones.
+> First, we need to create the `<module_dir>/etc/sales.xml` file in our module. This file is applied for registration of all the available Magento totals.
+>
+> The below examples are how default Magento uses this to add the basic totals:
+
+![Magento Section Chevron](./images/icon-chevron.png)[Magento_Quote](https://devdocs.magento.com/guides/v2.3/mrg/ce/Quote.html&sa=D&ust=1609223265766000&usg=AOvVaw36Ia-BIL2xfbyCg2rX160B)::etc/sales.xml
+
+> Default `subtotals`, `shipping` & `grand_totals` on Quote:
+
+```xml
+<?xml version="1.0"?>
+
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Sales:etc/sales.xsd">
+    <section name="quote">
+        <group name="totals">
+            <item name="subtotal" instance="Magento\Quote\Model\Quote\Address\Total\Subtotal" sort_order="100"/>
+            <item name="shipping" instance="Magento\Quote\Model\Quote\Address\Total\Shipping" sort_order="350"/>
+            <item name="grand_total" instance="Magento\Quote\Model\Quote\Address\Total\Grand" sort_order="550"/>
+        </group>
+    </section>
+</config>
+```
+
+**Quote/Cart**
+
+> Totals collector class:
+
+```php
+Magento\Quote\Model\Quote\TotalsCollector::collect(
+    \Magento\Quote\Model\Quote $quote
+)
+```
+
+![Magento Exam Information](./images/icon-info.png) `Magento\Quote\Model\Quote\TotalsCollector::collectQuoteTotals` not used
+
+1.  Create totalsCollector.collect factory to crunch numbers, return data to set on Quote.
+2.  Create Quote Totals object `Magento\Quote\Model\Cart\Totals`. All you set here will be copied to quote.
+3.  Dispatch event: `sales_quote_collect_totals_before`
+4.  Collect Quote/Cart Item `qtys`, `itemsCount`, `itemsQty`, `virtualItemsQty`, zero total object amounts, subtotal, grand total etc
+5.  Collect each Quote/Cart Address Totals: Collect address totals into new address total object address total = `quote.collectAddressTotals` (see below
+6.  Add to Quote/Cart totals object the following: shipping amount, shipping description, subtotal, subtotal with discount, grant total (+ base versions when applicable)
+7.  Validate max grand total amount 99999999
+8.  Validate coupon code - check that at least one address has it, otherwise reset to '' - code is
+9.  Dispatch event: `sales_quote_collect_totals_after`
+10.  `Magento\Quote\Model\Quote::addData(Magento\Quote\Model\Cart\Totals::getData())`
+
+
+**Quote/Cart Address**
+
+> Totals collector class:
+
+```php
+Magento\Quote\Model\Quote\TotalsCollector::collectAddressTotals(
+    \Magento\Quote\Model\Quote $quote,
+    \Magento\Quote\Model\Quote\Address $address
+)
+```
+
+1.  `Magento\Quote\Model\Quote\TotalsCollector::collectAddressTotals` for each address (billing, shipping) - set address fields, return some fields for the Quote/Cart
+2.  New shipping assignment object:
+
+    *  shipping = [method, address
+    *  items = address items. empty for normal checkout?
+
+3.  Create a new Address Totals object `Magento\Quote\Model\Quote\Address\Total` - All you set here will be copied to the Quote/Cart Address.
+4.  Dispatch event: `sales_quote_address_collect_totals_before`
+5.  Get Totals Collectors (all data set on the Quote/Cart Address Total object will be copied to the Quote/Cart Address object. Main amounts will also copy to Quote Totals object):
+
+    *  `_initModels` -> `_initModelInstance` -> `model.processConfigArray` -- tax collector can change its sort programmatically
+    *  `sales/totals_sort/*` - admin configurable totals retrievers ordering - display
+    *  Every `collector[].collect`
+
+6.  Address Totals object has direct access to
+7.  Address Totals object has access to Quote/Cart Address via shipping `assignment.getShipping`.
+8.  Dispatch event: `sales_quote_address_collect_totals_after`
+9.  `Magento\Quote\Model\Quote\Address::addData(Magento\Quote\Model\Quote\Address\Total.getData())`
+
+![Magento Section Chevron](./images/icon-chevron.png)[Magento_Sales](https://devdocs.magento.com/guides/v2.3/mrg/ce/Sales.html&sa=D&ust=1609223265775000&usg=AOvVaw2XF-Kl-6Epn71FzU0J_vzq)::etc/sales.xml
+
+Default `subtotals`, `shipping`, `discounts`, `tax`, `costs` and `grand_totals` on Order Invoices and Order Credit Memo. Available for [Simple](#h.cbgifdse6zd5) and [Virtual](#h.t3fkw0wf3trp) Products:
+
+
+```xml
+<?xml version="1.0"?>
+
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Sales:etc/sales.xsd">
+    <section name="order_invoice">
+        <group name="totals">
+            <item name="subtotal" instance="Magento\Sales\Model\Order\Invoice\Total\Subtotal" sort_order="50"/>
+            <item name="discount" instance="Magento\Sales\Model\Order\Invoice\Total\Discount" sort_order="100"/>
+            <item name="shipping" instance="Magento\Sales\Model\Order\Invoice\Total\Shipping" sort_order="150"/>
+            <item name="tax" instance="Magento\Sales\Model\Order\Invoice\Total\Tax" sort_order="200"/>
+            <item name="cost_total" instance="Magento\Sales\Model\Order\Invoice\Total\Cost" sort_order="250"/>
+            <item name="grand_total" instance="Magento\Sales\Model\Order\Invoice\Total\Grand" sort_order="350"/>
+        </group>
+    </section>
+    <section name="order_creditmemo">
+        <group name="totals">
+            <item name="subtotal" instance="Magento\Sales\Model\Order\Creditmemo\Total\Subtotal" sort_order="50"/>
+            <item name="discount" instance="Magento\Sales\Model\Order\Creditmemo\Total\Discount" sort_order="150"/>
+            <item name="shipping" instance="Magento\Sales\Model\Order\Creditmemo\Total\Shipping" sort_order="200"/>
+            <item name="tax" instance="Magento\Sales\Model\Order\Creditmemo\Total\Tax" sort_order="250"/>
+            <item name="cost_total" instance="Magento\Sales\Model\Order\Creditmemo\Total\Cost" sort_order="300"/>
+            <item name="grand_total" instance="Magento\Sales\Model\Order\Creditmemo\Total\Grand" sort_order="400"/>
+        </group>
+    </section>
+    <order>
+        <available_product_type name="simple"/>
+        <available_product_type name="virtual"/>
+    </order>
+</config>
+```
+
+**Invoice**
+
+> Totals collector class: `Magento\Sales\Model\Order\Invoice::collectTotals()`
+
+```php
+Magento\Sales\Model\Order\Invoice\Total\AbstractTotal::collect(
+    \Magento\Sales\Model\Order\Invoice $invoice
+)
+```
+
+**Credit Memo**
+
+> Totals collector class: `Magento\Sales\Model\Order\Creditmemo::collectTotals()`
+
+```php
+Magento\Sales\Model\Order\Creditmemo\Total\AbstractTotal::collect
+    \Magento\Sales\Model\Order\Creditmemo $creditmemo
+)
+```
+
+**Display totals**
+
+> Totals rendered in cart in UI-component fashion with JS Configuration.
+>
+> Totals JS models extend the following class:
+>
+> `Magento_Checkout/js/view/summary/abstract-total`
+>
+> & implement:
+
+*   `getPureValue` - raw float
+*   `getValue` - formatted via Magento_Catalog/js/price-utils in format window.checkoutConfig.priceFormat.
+
+> Models get their values from model `quote.getTotals()`, e.g.
+>
+> `quote.getTotals()().subtotal`.
+>
+> Initial totals values are available in
+>
+> `window.checkoutConfig.totalsData`
+>
+> & extended attributes are merged into main totals.
+>
+> `window.checkoutConfig` values are provided by the following PHP classes:
+>
+> `Magento\Checkout\Model\CompositeConfigProvider` - [Composite Product](#h.cbgifdse6zd5) config provider `Magento\Checkout\Model\DefaultConfigProvider` - Default config provider
+>
+> To extend config providers you must register your classes via arguments.
+>
+> Finally, the Default config `provider.getTotalsData` method and REST API re-uses the same [Repository](#h.5y2r6c8djm3h) which starts the process mentioned above (see the Quote/Cart Totals collector example).
+
+![Magento Section Chevron](./images/icon-chevron.png)[Magento_Tax](https://devdocs.magento.com/guides/v2.3/mrg/ce/Tax.html&sa=D&ust=1609223265784000&usg=AOvVaw2XyaB1BynDZoUFL2BIvU8a)::etc/sales.xml
+
+> Default Quote totals calculation for `tax`, `tax_subtotals`, `tax_shipping`, `subtotal`, `shipping`, `discount` and `grand_totals`:
+
+```xml
+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Sales:etc/sales.xsd">
+    <section name="quote">
+        <group name="totals">
+            <item name="tax_subtotal" instance="Magento\Tax\Model\Sales\Total\Quote\Subtotal" sort_order="200"/>
+            <item name="tax_shipping" instance="Magento\Tax\Model\Sales\Total\Quote\Shipping" sort_order="375"/>
+            <item name="tax" instance="Magento\Tax\Model\Sales\Total\Quote\Tax" sort_order="450">
+                <renderer name="adminhtml" instance="Magento\Sales\Block\Adminhtml\Order\Create\Totals\Tax"/>
+                <renderer name="frontend" instance="Magento\Tax\Block\Checkout\Tax"/>
+            </item>
+            <item name="subtotal">
+                <renderer name="adminhtml" instance="Magento\Sales\Block\Adminhtml\Order\Create\Totals\Subtotal"/>
+                <renderer name="frontend" instance="Magento\Tax\Block\Checkout\Subtotal"/>
+            </item>
+            <item name="shipping">
+                <renderer name="adminhtml" instance="Magento\Sales\Block\Adminhtml\Order\Create\Totals\Shipping"/>
+                <renderer name="frontend" instance="Magento\Tax\Block\Checkout\Shipping"/>
+            </item>
+            <item name="discount">
+                <renderer name="adminhtml" instance="Magento\Sales\Block\Adminhtml\Order\Create\Totals\Discount"/>
+                <renderer name="frontend" instance="Magento\Tax\Block\Checkout\Discount"/>
+            </item>
+            <item name="grand_total">
+                <renderer name="adminhtml" instance="Magento\Sales\Block\Adminhtml\Order\Create\Totals\Grandtotal"/>
+                <renderer name="frontend" instance="Magento\Tax\Block\Checkout\Grandtotal"/>
+            </item>
+        </group>
+    </section>
+</config>
+```
+![Magento Section Chevron](./images/icon-chevron.png)[Magento_Weee](https://devdocs.magento.com/guides/v2.3/mrg/ce/Weee.html&sa=D&ust=1609223265788000&usg=AOvVaw3Wer_jZlM-Cr5wST5WdpfM)::etc/sales.xml
+
+> Default [Magento_Weee](https://devdocs.magento.com/guides/v2.3/mrg/ce/Weee.html&sa=D&ust=1609223265789000&usg=AOvVaw1xFFD0cm0LBgfrHreOpybl) fees/fixed product taxes (FPT) on certain types of products on Quote, Order Invoice & Order Credit Memo example:
+
+```xml
+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Sales:etc/sales.xsd">
+    <section name="quote">
+        <group name="totals">
+            <item name="weee" instance="Magento\Weee\Model\Total\Quote\Weee" sort_order="225"/>
+            <item name="weee_tax" instance="Magento\Weee\Model\Total\Quote\WeeeTax" sort_order="460"/>
+        </group>
+    </section>
+    <section name="order_invoice">
+        <group name="totals">
+            <item name="weee" instance="Magento\Weee\Model\Total\Invoice\Weee" sort_order="600"/>
+        </group>
+    </section>
+    <section name="order_creditmemo">
+        <group name="totals">
+            <item name="weee" instance="Magento\Weee\Model\Total\Creditmemo\Weee" sort_order="100"/>
+        </group>
+    </section>
+</config>
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)[Magento_SalesRule](https://devdocs.magento.com/guides/v2.3/mrg/ce/SalesRule.html&sa=D&ust=1609223265792000&usg=AOvVaw0yBiIKRU3qXytSrNS0J9Vz)::etc/sales.xml
+
+> Sales Rule totals, discounts and shipping discounts for Quote available for [Configurable Products](#h.98cgcmsgdbu5):
+
+```xml
+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Sales:etc/sales.xsd">
+    <section name="quote">
+        <group name="totals">
+            <item name="discount" instance="Magento\SalesRule\Model\Quote\Discount" sort_order="300"/>
+            <item name="shipping_discount" instance="Magento\SalesRule\Model\Quote\Address\Total\ShippingDiscount" sort_order="400"/>
+        </group>
+    </section>
+</config>
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)[Magento_ConfigurableProduct](https://devdocs.magento.com/guides/v2.3/mrg/ce/ConfigurableProduct.html&sa=D&ust=1609223265793000&usg=AOvVaw1bYzvZxfK_ejsFruecW3uG)::etc/sales.xml
+
+> Allowing default sales totals objects (defined previously) for [Configurable Products](#h.98cgcmsgdbu5):
+
+```xml
+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Sales:etc/sales.xsd">
+    <order>
+        <available_product_type name="configurable"/>
+    </order>
+</config>
+```
+
+
+![Magento Section Chevron](./images/icon-chevron.png)[Magento_Bundle](https://devdocs.magento.com/guides/v2.3/mrg/ce/Bundle.html&sa=D&ust=1609223265795000&usg=AOvVaw13Xm7RUCSzcY66bFv8TK7e)::etc/sales.xml
+
+> Allowing default sales totals objects (defined previously) for [Bundle Products](#h.41g7zcfrlmri):
+
+```xml
+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Sales:etc/sales.xsd">
+    <order>
+        <available_product_type name="bundle"/>
+    </order>
+</config>
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)[Magento_Downloadable](https://devdocs.magento.com/guides/v2.3/mrg/ce/Downloadable.html&sa=D&ust=1609223265797000&usg=AOvVaw0COgtorvSjRXGnHZpjbCDR)::etc/sales.xml
+
+> Allowing default sales totals objects (defined previously) for [Downloadable Products](#h.614rvm49j6y9):
+
+```xml
+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Sales:etc/sales.xsd">
+    <order>
+        <available_product_type name="downloadable"/>
+    </order>
+</config>
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)[Magento_GroupedProduct](https://devdocs.magento.com/guides/v2.3/mrg/ce/GroupedProduct.html&sa=D&ust=1609223265799000&usg=AOvVaw1TSEdgAOVaqshRXb0USfBr)::etc/sales.xml
+
+> Allowing default sales totals objects (defined previously) for [Grouped Products](#h.pedurdgu5za5):
+
+```xml
+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Sales:etc/sales.xsd">
+    <order>
+        <available_product_type name="grouped"/>
+    </order>
+</config>
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)[Magento_GiftCard](https://devdocs.magento.com/guides/v2.3/mrg/ee/GiftCard.html&sa=D&ust=1609223265800000&usg=AOvVaw3G5q4KapL5kpTv67kDSZqm)::etc/sales.xml (Magento Commerce/Enterprise only)
+
+> Allowing default sales totals objects (defined previously) for [Giftcard Products](#h.87l1vab27p5t):
+
+```xml
+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Sales:etc/sales.xsd">
+    <order>
+        <available_product_type name="giftcard"/>
+    </order>
+</config>
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)[Magento_GiftCardAccount](https://devdocs.magento.com/guides/v2.3/mrg/ee/GiftCardAccount.html&sa=D&ust=1609223265801000&usg=AOvVaw2xWqBEjFbnvvA7QcBxCVGW)::etc/sales.xml (Magento Commerce/Enterprise only)
+
+> Defining total giftcard amount objects for [Magento Giftcards](https://docs.magento.com/user-guide/catalog/product-gift-card-create.html&sa=D&ust=1609223265802000&usg=AOvVaw2giqaglD6JFR0Ont1hjzcE) on Quote, Order Invoice, Order and Credit Memos:
+
+```xml
+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Sales:etc/sales.xsd">
+    <section name="quote">
+        <group name="totals">
+            <item name="giftcardaccount" instance="Magento\GiftCardAccount\Model\Total\Quote\Giftcardaccount" sort_order="700">
+                <renderer name="frontend" instance="Magento\GiftCardAccount\Block\Checkout\Cart\Total"/>
+            </item>
+        </group>
+    </section>
+    <section name="order_invoice">
+        <group name="totals">
+            <item name="giftcardaccount" instance="Magento\GiftCardAccount\Model\Total\Invoice\Giftcardaccount" sort_order="500"/>
+        </group>
+    </section>
+    <section name="order_creditmemo">
+        <group name="totals">
+            <item name="giftcardaccount" instance="Magento\GiftCardAccount\Model\Total\Creditmemo\Giftcardaccount" sort_order="500"/>
+        </group>
+    </section>
+</config>
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)[Magento_CustomerBalance](https://devdocs.magento.com/guides/v2.3/mrg/ee/CustomerBalance.html&sa=D&ust=1609223265805000&usg=AOvVaw0K2ggPeOXzHMBsPbLX7Jqm)::etc/sales.xml (Magento Commerce/Enterprise only)
+
+> Defining total customer balance objects for [Magento Store Credit](https://docs.magento.com/user-guide/sales/store-credit.html&sa=D&ust=1609223265806000&usg=AOvVaw0PKZDkdfIPICiYaSzRwjr3) on Quote, Order Invoice, Order and Credit Memos:
+
+```xml
+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Sales:etc/sales.xsd">
+    <section name="quote">
+        <group name="totals">
+            <item name="customerbalance" instance="Magento\CustomerBalance\Model\Total\Quote\Customerbalance" sort_order="750">
+                <renderer name="frontend" instance="Magento\CustomerBalance\Block\Checkout\Total"/>
+            </item>
+        </group>
+    </section>
+    <section name="order_invoice">
+        <group name="totals">
+            <item name="customerbalance" instance="Magento\CustomerBalance\Model\Total\Invoice\Customerbalance" sort_order="550"/>
+        </group>
+    </section>
+    <section name="order_creditmemo">
+        <group name="totals">
+            <item name="customerbalance" instance="Magento\CustomerBalance\Model\Total\Creditmemo\Customerbalance" sort_order="450"/>
+        </group>
+    </section>
+</config>
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)[Magento_Reward](https://devdocs.magento.com/guides/v2.3/mrg/ee/Reward.html&sa=D&ust=1609223265809000&usg=AOvVaw2wXRRK9TuEvOWIps1tRCY5)::etc/sales.xml (Magento Commerce/Enterprise only)
+
+> Defining total reward points objects for [Magento Store Credit](https://docs.magento.com/user-guide/sales/store-credit.html&sa=D&ust=1609223265810000&usg=AOvVaw1wNUcEVszesfyJinFLNgBH) on Quote, Order Invoice, Order and Credit Memos:
+
+```xml
+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Sales:etc/sales.xsd">
+    <section name="quote">
+        <group name="totals">
+            <item name="reward" instance="Magento\Reward\Model\Total\Quote\Reward" sort_order="1000">
+                <renderer name="frontend" instance="Magento\Reward\Block\Checkout\Total"/>
+            </item>
+        </group>
+    </section>
+    <section name="order_invoice">
+        <group name="totals">
+            <item name="reward" instance="Magento\Reward\Model\Total\Invoice\Reward" sort_order="450"/>
+        </group>
+    </section>
+    <section name="order_creditmemo">
+        <group name="totals">
+            <item name="reward" instance="Magento\Reward\Model\Total\Creditmemo\Reward" sort_order="550"/>
+        </group>
+    </section>
+</config>
+
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)[Magento_GiftWrapping](https://devdocs.magento.com/guides/v2.3/mrg/ee/GiftWrapping.html&sa=D&ust=1609223265814000&usg=AOvVaw1TvfwtuZA2RzCtukevqN8_)::etc/sales.xml (Magento Commerce/Enterprise only)
+
+> Defining [Magento Gift Wrapping](https://docs.magento.com/user-guide/sales/gift-wrap.html&sa=D&ust=1609223265814000&usg=AOvVaw1JfNhTm_O2jBLneEy_qadY) totals & tax objects on Quote, Order Invoice, Order and Credit Memos:
+
+```xml
+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Sales:etc/sales.xsd">
+    <section name="quote">
+        <group name="totals">
+            <item name="giftwrapping" instance="Magento\GiftWrapping\Model\Total\Quote\Giftwrapping" sort_order="190">
+                <renderer name="frontend" instance="Magento\GiftWrapping\Block\Checkout\Totals"/>
+            </item>
+            <item name="pretax_giftwrapping" instance="Magento\GiftWrapping\Model\Total\Quote\Tax\Giftwrapping" sort_order="425"/>
+            <item name="tax_giftwrapping" instance="Magento\GiftWrapping\Model\Total\Quote\Tax\GiftwrappingAfterTax" sort_order="475"/>
+        </group>
+    </section>
+    <section name="order_invoice">
+        <group name="totals">
+            <item name="giftwrapping" instance="Magento\GiftWrapping\Model\Total\Invoice\Giftwrapping" sort_order="400"/>
+            <item name="tax_giftwrapping" instance="Magento\GiftWrapping\Model\Total\Invoice\Tax\Giftwrapping" sort_order="300"/>
+        </group>
+    </section>
+    <section name="order_creditmemo">
+        <group name="totals">
+            <item name="giftwrapping" instance="Magento\GiftWrapping\Model\Total\Creditmemo\Giftwrapping" sort_order="450"/>
+            <item name="tax_giftwrapping" instance="Magento\GiftWrapping\Model\Total\Creditmemo\Tax\Giftwrapping" sort_order="350"/>
+        </group>
+    </section>
+</config>
+```
+
+![Magento Exam Information](./images/icon-info.png)Remember the exam is multiple choice here, you won't be expected to memorise all this. It's for demonstration purposes only.
+
+![Magento Exam Question](./images/icon-question.png)**Describe how to modify the price calculation process in the shopping cart. How can you add a custom totals model or modify existing totals models?**
+
+> There are a few ways you can modify totals in the shopping cart:
+
+1.  `Method: Magento\Quote\Model\Quote\Item::setCustomPrice` which can be set in an [Observer](#h.y2lezqicnwxl), event: [checkout_cart_product_add_after](https://store.magenest.com/blog/set-custom-price-products-cart-magento-2/&sa=D&ust=1609223265817000&usg=AOvVaw1_z229NQgWnW-9VcsniWnf) for example.
+2.  Create a Sales / [Cart Price Rule](#h.x0kvcqk03fp8).
+3.  Create a Custom Totals object.
+
+> Depending on the task at hand, either of these approaches may better suit the requirements. For modifying the calculation process specifically however, creating a Custom Totals object is the best option. Custom Totals can be used to add an additional tax or discount in Magento Checkout or modify the existing ones.
+>
+> Here's an example:
+
+`<module_dir>/etc/sales.xml`
+```xml
+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Sales:etc/sales.xsd">
+   <section name="quote">
+       <group name="totals">
+           <item name="custom_total" instance="MyVendor\MyModule\Model\Totals\Custom" sort_order="500"/>
+       </group>
+   </section>
+</config>
+```
+
+> Here, we set `MyVendor\MyModule\Model\Totals\Custom` class as the model of our custom total. This class should inherit `Magento\Quote\Model\Quote\Address\Total\AbstractTotal` and realise methods: collect and fetch.
+> The collect method is applied to calculate our total, while the fetch method returns the value together with total's code and its name.
+>
+> Also, `Magento\Quote\Model\Quote\Address\Total $total` parameter allows you to affect the result of the other total classes. But, depending on the task, it may be reasonable to use plugins to modify their values.
+
+`<module_dir>/Model/Total/Custom.php`
+
+```php
+<?php
+
+namespace MyVendor\MyModule\Model\Total;
+
+class Custom extends \Magento\Quote\Model\Quote\Address\Total\AbstractTotal
+{
+
+    public function __construct()
+    {
+        $this->setCode('custom_total');
+    }
+
+    /**
+     * @param \Magento\Quote\Model\Quote $quote
+     * @param \Magento\Quote\Api\Data\ShippingAssignmentInterface $shippingAssignment
+     * @param \Magento\Quote\Model\Quote\Address\Total $total
+     * @return $this
+     */
+    public function collect(
+        \Magento\Quote\Model\Quote $quote,
+        \Magento\Quote\Api\Data\ShippingAssignmentInterface $shippingAssignment,
+        \Magento\Quote\Model\Quote\Address\Total $total
+    ) {
+        parent::collect($quote, $shippingAssignment, $total);
+
+        $items = $shippingAssignment->getItems();
+        if (!count($items)) {
+            return $this;
+        }
+
+        //we will add an additional amount of 150 to the order as an example
+        $amount = 150;
+
+        $total->setTotalAmount('custom_total', $amount);
+        $total->setBaseTotalAmount('custom_total', $amount);
+        $total->setCustomAmount($amount);
+        $total->setBaseCustomAmount($amount);
+        $total->setGrandTotal($total->getGrandTotal() + $amount);
+        $total->setBaseGrandTotal($total->getBaseGrandTotal() + $amount);
+        return $this;
+    }
+
+    /**
+     * @param \Magento\Quote\Model\Quote\Address\Total $total
+     */ protected function clearValues(\Magento\Quote\Model\Quote\Address\Total  $total)
+    {
+        $total->setTotalAmount('subtotal', 0);
+        $total->setBaseTotalAmount('subtotal', 0);
+        $total->setTotalAmount('tax', 0);
+        $total->setBaseTotalAmount('tax', 0);
+        $total->setTotalAmount('discount_tax_compensation', 0);
+        $total->setBaseTotalAmount('discount_tax_compensation', 0);
+        $total->setTotalAmount('shipping_discount_tax_compensation', 0);
+        $total->setBaseTotalAmount('shipping_discount_tax_compensation', 0);
+        $total->setSubtotalInclTax(0);
+        $total->setBaseSubtotalInclTax(0);
+    }
+
+    /**
+     * @param \Magento\Quote\Model\Quote $quote
+     * @param \Magento\Quote\Model\Quote\Address\Total $total
+     * @return array
+     */ public function fetch(
+        \Magento\Quote\Model\Quote  $quote,
+        \Magento\Quote\Model\Quote\Address\Total $total
+    ) {
+        return [
+            'code' => $this->getCode(),
+            'title' => 'Custom Total',
+            'value' => 150
+        ];
+    }
+
+    /**
+     * @return Magento\Framework\Phrase
+     */ public function getLabel()
+    {
+        return __('Custom Total');
+    }
+}
+```
+
+![Magento Exam Question](./images/icon-question.png)**How would you display this custom totals object?**
+
+![Magento Section Chevron](./images/icon-chevron.png)Checkout & Cart
+
+> Displaying this Custom Totals object in the Cart and Checkout pages is done using knockout.js.
+> Therefore, to make our total appear at the cart and checkout pages, we need to add a new JS component into checkout_cart_index.xml and checkout_index_index.xml layouts:
+
+`<module_dir>/view/frontend/layout/checkout_cart_index.xml`
+
+```xml
+<?xml version="1.0"?>
+<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
+    <body>
+        <referenceBlock name="checkout.cart.totals">
+            <arguments>
+                <argument name="jsLayout" xsi:type="array">
+                    <item name="components" xsi:type="array">
+                        <item name="block-totals" xsi:type="array">
+                            <item name="children" xsi:type="array">
+                                <item name="custom_total" xsi:type="array">
+                                    <item name="component" xsi:type="string">Vendor_Module/js/view/checkout/cart/totals/custom_total</item>
+                                    <item name="sortOrder" xsi:type="string">20</item>
+                                    <item name="config" xsi:type="array">
+                                        <item name="template" xsi:type="string">Vendor_Module/checkout/cart/totals/custom_total</item>
+                                        <item name="title" xsi:type="string">Custom Total</item>
+                                    </item>
+                                </item>
+                            </item>
+                        </item>
+                    </item>
+                </argument>
+            </arguments>
+        </referenceBlock>
+    </body>
+</page>
+```
+
+`<module_dir>/view/frontend/layout/checkout_index_index.xml`
+
+```xml
+<?xml version="1.0"?>
+<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" layout="1column" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
+   <body>
+       <referenceBlock name="checkout.root">
+           <arguments>
+               <argument name="jsLayout" xsi:type="array">
+                   <item name="components" xsi:type="array">
+                       <item name="checkout" xsi:type="array">
+                           <item name="children" xsi:type="array">
+                               <item name="sidebar" xsi:type="array">
+                                   <item name="children" xsi:type="array">
+                                       <item name="summary" xsi:type="array">
+                                           <item name="children" xsi:type="array">
+                                               <item name="totals" xsi:type="array">
+                                                   <item name="children" xsi:type="array">
+                                                       <item name="custom_total" xsi:type="array">
+                                                           <item name="component"  xsi:type="string">Vendor_Module/js/view/checkout/cart/totals/custom_total</item>
+                                                           <item name="sortOrder" xsi:type="string">20</item>
+                                                           <item name="config" xsi:type="array">
+                                                               <item name="template" xsi:type="string">Vendor_Module/checkout/cart/totals/custom_total</item>
+                                                               <item name="title" xsi:type="string">Custom Total</item>
+                                                           </item>
+                                                       </item>
+                                                   </item>
+                                               </item>
+                                               <item name="cart_items" xsi:type="array">
+                                                   <item name="children" xsi:type="array">
+                                                       <item name="details" xsi:type="array">
+                                                           <item name="children" xsi:type="array">
+                                                               <item name="subtotal" xsi:type="array">
+                                                                   <item name="component" xsi:type="string">Magento_Tax/js/view/checkout/summary/item/details/subtotal</item>
+                                                               </item>
+                                                           </item>
+                                                       </item>
+                                                   </item>
+                                               </item>
+                                           </item>
+                                       </item>
+                                   </item>
+                               </item>
+                           </item>
+                       </item>
+                   </item>
+               </argument>
+           </arguments>
+       </referenceBlock>
+   </body>
+</page>
+```
+
+> We can also create the components themselves, together with HTML templates:
+
+`<module_dir>/view/frontend/web/js/view/checkout/cart/totals/custom_total.js`
+
+```js
+
+define(
+    [
+        'Vendor_Module/js/view/checkout/summary/custom_total'
+    ],
+    function (
+        Component
+    ) {
+
+        'use strict';
+        return Component.extend({
+
+                /**
+                 * @override
+                 */
+                isDisplayed: function () {
+
+                    return this.getPureValue() !== 0;
+                }
+        });
+    }
+);
+```
+
+`<module_dir>/view/frontend/web/template/checkout/cart/totals/custom_total.html`
+
+```html
+<!-- ko if: isDisplayed() -->
+<tr class="totals custom_total excl">
+   <th class="mark" colspan="1" scope="row" data-bind="text: title"></th>
+   <td class="amount">
+       <span class="price" data-bind="text: getValue()"></span>
+   </td>
+</tr>
+<!-- /ko -->
+```
+
+`<module_dir>/view/frontend/web/js/view/checkout/summary/custom_total.js`
+
+```js
+define(
+    [
+        'Magento_Checkout/js/view/summary/abstract-total',
+        'Magento_Checkout/js/model/quote',
+        'Magento_Catalog/js/price-utils',
+        'Magento_Checkout/js/model/totals'
+    ],
+    function (
+        Component,
+        quote,
+        priceUtils,
+        totals
+    ) {
+        "use strict";
+
+        return Component.extend({
+
+            defaults: {
+                isFullTaxSummaryDisplayed: window.checkoutConfig.isFullTaxSummaryDisplayed || false,
+                template: 'Vendor_Module/checkout/summary/custom_total'
+            },
+
+            totals: quote.getTotals(),
+
+            isTaxDisplayedInGrandTotal: window.checkoutConfig.includeTaxInGrandTotal || false,
+
+            isDisplayed: function () {
+
+                return this.isFullMode() && this.getPureValue() !== 0;
+            },
+
+            getValue: function () {
+
+                var price = 0; if (this.totals()) {
+                    price = totals.getSegment('custom_total').value;
+                }
+
+                return this.getFormattedPrice(price);
+            },
+            getPureValue: function () {
+
+                var price = 0; if (this.totals()) {
+                    price = totals.getSegment('custom_total').value;
+                }
+
+                return price;
+            }
+        });
+    }
+);
+```
+
+> `getValue` and `getPureValue` methods return the values of our custom total, but getValue method formats the value, adding two decimal digits and the actual currency symbol.
+
+`<module_dir>/view/frontend/web/template/checkout/summary/custom_total.html`
+
+```html
+<!-- ko if: isDisplayed() -->
+<tr class="totals custom_total excl">
+    <th class="mark" scope="row">
+        <span class="label" data-bind="text: title"></span>
+        <span class="value" data-bind="text: getValue()"></span>
+    </th>
+    <td class="amount">
+        <span class="price" data-bind="text: getValue(), attr: {'data-th': title}"></span>
+    </td>
+</tr>
+<!-- /ko -->
+```
+
+![Magento Section Chevron](./images/icon-chevron.png)Sales Order Emails
+
+> To add a new total display into order email, add a new block in `sales_email_order_items` layout.
+
+`<module_dir>/view/frontend/layout/sales_email_order_items.xml`
+
+```xml
+<?xml version="1.0" encoding="UTF-8"?>
+<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
+    <body>
+        <referenceBlock name="order_totals">
+            <block class="Vendor\Module\Block\Order\CustomTotal" name="order.totals.custom" />
+        </referenceBlock>
+    </body>
+</page>
+```
+
+`<module_dir>/Block/Order/CustomTotal.php`
+
+```php
+<?php
+
+namespace Vendor\Module\Block\Order;
+
+class CustomTotal extends Magento\Framework\View\Element\AbstractBlock
+{
+    public function initTotals()
+    {
+        $orderTotalsBlock = $this->getParentBlock();
+        $order = $orderTotalsBlock->getOrder();
+        if ($order->getCustomAmount() > 0) {
+            $orderTotalsBlock->addTotal(new Magento\Framework\DataObject([
+                'code'           => 'custom_total',
+                'label'      => __('Custom Total'),
+                'value'      => $order->getCustomAmount(),
+                'base_value' => $order->getCustomBaseAmount(),
+            ]), 'subtotal');
+        }
+    }
+}
+```
+
+![Magento Exam Information](./images/icon-info.png)Remember the exam is multiple choice here, you won't be expected to memorise all this. It's for demonstration purposes only.
+
+8.3 Demonstrate ability to customize the shopping cart
+------------------------------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**Describe the available shopping cart operations. Which operations are available to the customer on the cart page?**
+
+1.  Modify product quantity
+2.  Update the cart (required after the quantities are modified)
+3.  Modify configurable/bundle product options
+4.  Remove the product from the cart
+5.  Place the product into wishlist (if enabled)
+6.  Add / delete the coupon
+7.  Redeem a Giftcard (Magento Enterprise/Commerce only)
+8.  Specify Gift Options (Magento Enterprise/Commerce only)
+9.  Specify Gift Wrapping Options (Magento Enterprise/Commerce only)
+10.  Go to checkout
+11.  Go to multi-shipping settings (if enabled)
+
+### Cart Price Rules
+
+![Magento Exam Question](./images/icon-question.png)**Describe how to implement shopping cart rules. How would you create a Cart Price Rule?**
+
+#### ![Magento Section Chevron](./images/icon-chevron.png)Implementing Via Admin
+
+> Sales / Cart Price Rules (or Sales Price Rules) apply discounts to items in the shopping cart, based on a set of conditions. The discount can be applied automatically as soon as the conditions are met, or when the customer enters a valid coupon code. When applied, the discount appears in the cart under the subtotal. A Cart Price Rule can be used as needed for a season or promotion by changing its status and date range.
+>
+> Commonly, cart rules are created from the admin panel, but they can also be created programmatically.
+>
+> Log in to the admin panel and navigate to:
+>
+> **Admin > Marketing > Cart Price Rules > Click: "Add New Rule"**
+>
+> ![](./images/Magento-2-Certified-Professional-Developer-Guide-Cart-Price-Rules.jpg)
+>
+> Fill in the following Features / Actions & Conditions:
+
+![Magento Section Chevron](./images/icon-chevron.png)Cart Price Rule Features
+
+| Attribute | Backend Type / Frontend Type | Description |
+| --- | --- | --- |
+| `name` | varchar/Text | (Required) The name of the rule is for internal reference. |
+| `description` | varchar/TextArea | A description of the rule should include the purpose of the rule, and explain how it is used. |
+| `is_active` | int/YesNo | (Required) Determines if the rule is currently active in the store. Options: Yes / No |
+| `website_ids` | varchar/Multiselect | (Required) Identifies the websites where the rule can be used. |
+| `customer_group_ids` | varchar/Multiselect | (Required) Identifies the customer groups to which the rule applies. |
+| `coupon_type` | int/Select | (Required) Indicates if a coupon is associated with the rule. Options: No Coupon - No coupon is associated with the rule. Specific Coupon - A specific coupon is associated with the rule. Coupon Code - When prompted, enter the Coupon Code that the customer must enter to take advantage of the promotion. Use Auto Generation - Select the checkbox to automatically generate multiple coupon codes that can be used with the promotion. Auto - Displays the Coupons Information section to define the format of the coupon codes to be generated. |
+| `uses_per_customer` | int/Number | Determines how many times the coupon code can be used by the same registered customer who belongs to any selected customer group. Does not apply to guest shoppers who are members of the NOT LOGGED IN customer group, or to customers who shop without logging in to their accounts. For no limit, leave blank. |
+| `sort_order` | int/Number | A number that indicates the priority of this rule in relation to others. The highest priority is number 1. |
+| `is_rss` | int/YesNo | Determines if the promotion is included in your store's public RSS feed. Options:  Yes / No |
+| `from_time` (community/open source only) | datetime/DatePicker | The first date the coupon can be used. |
+| `to_time` (community/open source only) | datetime/DatePicker | The last date the coupon can be used. |
+
+![Magento Section Chevron](./images/icon-chevron.png) Cart Price Rule Conditions
+
+> Specifies the conditions that must be met before the cart price rule goes into action. If left blank, the rule applies to all products in the cart. Conditions can be based on any combination of cart and product attributes. However, customizable options cannot be referenced in cart price rule conditions.
+
+| Condition | Description |
+| --- | --- |
+| Product attribute combination | **Product Attribute** - The available product attributes depend on the [](https://docs.magento.com/user-guide/stores/attribute-product-create.html&sa=D&ust=1609223265859000&usg=AOvVaw3UcrB_gTppov7f1ba2z1WB) [setup of the attribute](https://docs.magento.com/user-guide/stores/attribute-product-create.html&sa=D&ust=1609223265859000&usg=AOvVaw3UcrB_gTppov7f1ba2z1WB). For an attribute to show in the list, **Use for Promo Rule Conditions** for the attribute MUST be set to Yes in your [](https://docs.magento.com/user-guide/stores/attribute-product-create.html&sa=D&ust=1609223265859000&usg=AOvVaw3UcrB_gTppov7f1ba2z1WB) [Storefront Properties](https://docs.magento.com/user-guide/stores/attribute-product-create.html&sa=D&ust=1609223265860000&usg=AOvVaw01VaTMMfSjJH5qakfzbEt1). |
+| Conditions Combination | Choose to create an additional set of All/Any and True/False conditions inside the existing condition. |
+| Cart Attributes | Subtotal, Subtotal (Excl Tax), Total Items Qty, Total Weight, Payment Method, Shipping Method, Shipping Postcode, Shipping Region, Shipping State/Province, Shipping Country. |
+| Customer Segment (enterprise/commerce only) | [Customer Segments](https://docs.magento.com/user-guide/marketing/customer-segments.html&sa=D&ust=1609223265861000&usg=AOvVaw0hqeK3gkaLmmY9k_4q9K3h) allow you to dynamically display promotions to specific customers, based on properties such as customer address, order history, shopping cart contents, and so on. |
+
+![Magento Section Chevron](./images/icon-chevron.png) Cart Price Rule Actions
+
+| Action | Backend Type / Frontend Type | Description |
+| --- | --- | --- |
+| `simple_action` | varchar/Select | Determines the type of calculation that is applied to the purchase. Options: **Percent of product price discount** - Discounts item by subtracting a percentage from the original price. For example: Enter 10 in Discount Amount for an updated price that is 10% less than the original price.**Fixed amount discount** - Discounts item by subtracting a fixed amount from the original price of each qualifying item in the cart. For example: Enter 10 in Discount Amount for an updated price that is $10 less than the original price.**Fixed amount discount for the whole cart** - Discounts the entire cart by subtracting a fixed amount from the cart subtotal. For example: Enter 10 in Discount Amount to subtract $10 from the cart subtotal. By default, the discount applies only to the cart subtotal. To apply the discount to the subtotal and shipping separately, see Apply to Shipping Amount.**Buy X Get Y Free (discount amount is Y)** - Defines a quantity that the customer must purchase to receive a quantity for free. (The Discount Amount is Y.) |
+| `discount_amount` | int/Number | (Required) The amount of discount that is offered. |
+| `discount_qty` | int/Number | Sets the maximum number of products that the discount can be applied to in the same purchase. |
+| `discount_step` | int/Number | Sets the number of products represented by X in a Buy X Get Y Free promotion. |
+| `apply_to_shipping` | int/YesNo | Determines if the discount is applied separately to the subtotal and shipping amounts. Otherwise, it is applied only to the subtotal. Options: Yes / No |
+| `stop_rules_processing` | int/YesNo | Determines if additional rules can be applied to this purchase. To prevent multiple discounts from being applied to the same purchase, select Yes. Options: Yes / No |
+| `simple_free_shipping` | varchar/Select | Determines if free shipping is included in the promotion, and if so, for which items. Options: **No** - Free shipping is not available when a coupon that is based on the rule is used. **For matching items only** - Free shipping is available only for specific items in the cart that match the rule. **For shipment with matching items** - Free shipping is available for the entire cart when a coupon that is based on the rule is used. |
+| `reward_points_delta` (enterprise/commerce only) | int/Number | Specifies the number of [](https://docs.magento.com/user-guide/marketing/rewards-loyalty.html&sa=D&ust=1609223265872000&usg=AOvVaw1ImEyqbt-ng6QVcPnKdp6d) [reward points](https://docs.magento.com/user-guide/marketing/rewards-loyalty.html&sa=D&ust=1609223265873000&usg=AOvVaw0PzYeEYlcKwljZYjKB7du7) that are earned by the customer whenever the price rule is applied. This is an [Extension Attribute](#h.2lcvcwr56aq). |
+
+![Magento Section Chevron](./images/icon-chevron.png) Cart Price Rule Labels
+
+> Default Rule Label for All Store Views - A default label that identifies the discount and can be used for all store views.
+>
+> Store View Specific Labels - If applicable, specifies a different label to identify the discount for each store view.
+
+Databases
+| Table | Notable Columns | Description
+| --- | --- | --- |
+| `salesrule` | Rule ID, Is Active, Name/Description, From/To dates, Uses per customer/Times Used, Conditions (serialized), Actions (serialized), Stop Further Processing, Priorities, Discount Actions/Amounts/Quantity, Coupon Type | The main entity table where most of the detailed information regarding its rules are held such as its actions, conditions, discount amounts. |
+| `salesrule_coupon` | Coupon ID, Rule ID, Coupon Code, Usage Limit, Times Used, Expiry Date | Where generated coupon codes are kept ready for use. |
+| `salesrule_customer` | Customer ID, Rule ID, Times Used | Contains all used rules per customer. In the field times_used you'll get your number for each customer. |
+| `salesrule_coupon_usage` | Customer ID, Coupon ID, Times Used. | Contains all used coupon codes per customer. In the field times_used you'll get your number for each customer. |
+| `salesrule_product_attribute` | Website ID, Attribute ID, Customer Group ID, Row ID | Used in the conditions section of a Cart Price Rule, when a "Product Attributes Combination" matches the set conditions. |
+| `sequence_salesrule` | Sequence Value - The value to increment the ID by | A number dedicated to incrementing the Cart Price Rule IDs by. |
+| `magento_banner_salesrule` (Magento Commerce/Enterprise only) | Banner ID, Rule ID | Used for [Dynamic Blocks in Price Rules](https://docs.magento.com/user-guide/cms/dynamic-blocks-price-rules.html&sa=D&ust=1609223265884000&usg=AOvVaw1Af53rwYszXVy8lRrz8In2). |
+| `salesrule_rule_cl` | Version ID of Materialized View (mview), Rule Entity ID | The Cart Price Rule change-log table is responsible for updating the products on which catalog rule will be applied. This table is populated with the changes ready to update catalogrule_product when the indexer runs. |
+
+![Magento Exam Information](./images/icon-info.png)Aggregated tables are for reporting purposes such as `salesrule_coupon_aggregated`
+
+![Magento Exam Information](./images/icon-info.png)Sequence tables are also used for Order Increment IDs, Shipments, Invoices, Credit Memo, Categories, Products, Blocks & CMS Pages. They are there to improve concurrency (I think), it goes faster than using MySQL auto allocation. E.g. you can grab 100 ids in a single update for batch loads, or preallocate an ID before inserting the real record etc.
+
+![Magento Exam Information](./images/icon-info.png)Unlike [Catalog Rule Product](#h.x0kvcqk03fp8), there are no replica tables associated with Cart Price Rules. This is likely because you don't really navigate Sales Rules like you would a category of products with applied Catalog Price Rules.
+
+![Magento Exam Information](./images/icon-info.png)The main thing to remember here is that Cart Price Rules adhere to the [Service Contracts](#h.i0qq8aqgijv7) design pattern, therefore all the necessary models for customisation are available within the `Api/` directory of the `Magento_Quote` & `Magento_SalesRule` modules. The main functions of these models to remember here are Cart Price Rules (C.R.U.D actions), assigning a Cart Price Rule to a Quote, assigning properties of a Cart Price Rule such as conditions, actions etc, managing coupons. Separate management interfaces exist for both logged in Customers & Guests.
+
+#### ![Magento Section Chevron](./images/icon-chevron.png)Implementing Programmatically
+
+**Magento_Rule**
+
+> Module [Magento_Rule](https://devdocs.magento.com/guides/v2.3/mrg/ce/Rule.html&sa=D&ust=1609223265887000&usg=AOvVaw0iL7wHGG0hoJFJSSytiGV1) provides abstract implementation of Rules and Rule Conditions that are extended by other modules, in particular by: [Magento_SalesRule](https://devdocs.magento.com/guides/v2.3/mrg/ce/SalesRule.html&sa=D&ust=1609223265887000&usg=AOvVaw2-OeJ-fopKpekPsghJoa-y), [Magento_CatalogRule](https://devdocs.magento.com/guides/v2.3/mrg/ce/CatalogRule.html&sa=D&ust=1609223265887000&usg=AOvVaw1tL31RBJg-iNf-jd_EjJVq). Conditions and Actions are serialized and implemented on a foundation of abstract rules of class [Magento\Rule\Model\AbstractModel](https://github.com/magento/magento2/tree/2.2-develop/app/code/Magento/Rule/Model/AbstractModel.php&sa=D&ust=1609223265888000&usg=AOvVaw3FiSmcRLkCELmFnLnVlyGM):
+
+*   Rule Conditions: [](https://github.com/magento/magento2/tree/2.2-develop/app/code/Magento/Rule/Model/Condition/AbstractCondition.php&sa=D&ust=1609223265888000&usg=AOvVaw3tNV3wSwSGNayVoNtYkOAp) [Magento\Rule\Model\Condition\AbstractCondition](https://github.com/magento/magento2/tree/2.2-develop/app/code/Magento/Rule/Model/Condition/AbstractCondition.php&sa=D&ust=1609223265888000&usg=AOvVaw3tNV3wSwSGNayVoNtYkOAp), [](https://github.com/magento/magento2/tree/2.2-develop/app/code/Magento/Rule/Model/Condition/Combine.php&sa=D&ust=1609223265889000&usg=AOvVaw0vKJGxmi0DGiDTf7Iu4bp4) [combine](https://github.com/magento/magento2/tree/2.2-develop/app/code/Magento/Rule/Model/Condition/Combine.php&sa=D&ust=1609223265889000&usg=AOvVaw0vKJGxmi0DGiDTf7Iu4bp4)
+*   Rule Actions: [](https://github.com/magento/magento2/tree/2.2-develop/app/code/Magento/Rule/Model/Action/AbstractAction.php&sa=D&ust=1609223265889000&usg=AOvVaw2UkCUhI49VHtfCNzxixyxy) [Magento\Rule\Model\Action\AbstractAction](https://github.com/magento/magento2/tree/2.2-develop/app/code/Magento/Rule/Model/Action/AbstractAction.php&sa=D&ust=1609223265890000&usg=AOvVaw2EzIo7x10Nq2TlvbeYCry9), collection
+
+**Service Contracts**
+
+> Like the other Modules, Magento_SalesRule uses the [Service Contracts](#h.i0qq8aqgijv7) design pattern to manage (C.R.U.D actions) Cart Price Rules with the following Repositories:
+
+```php
+Magento\SalesRule\Api\RuleRepositoryInterface::save(
+    \Magento\SalesRule\Api\Data\RuleInterface $rule
+);
+```
+
+> Cart Price Coupons are a separate entity managed (C.R.U.D actions) by the following class:
+
+```php
+Magento\SalesRule\Api\CouponRepositoryInterface::save(
+    \Magento\SalesRule\Api\Data\CouponInterface $coupon
+);
+```
+
+> You can also use the following class to generate / remove coupon codes for Cart Price Rules:
+```php
+Magento\SalesRule\Api\CouponManagementInterface::generate(
+    \Magento\SalesRule\Api\Data\CouponGenerationSpecInterface $couponSpec
+);
+```
+
+> Return information on a coupon in a specified cart for a Guest:
+
+```php
+Magento\Quote\Api\GuestCouponManagementInterface::get(
+    $cartId
+);
+```
+
+> Return information on a coupon in a specified cart:
+
+```php
+Magento\Quote\Api\CouponManagementInterface::get(
+    $cartId
+);
+```
+
+> Rule Conditions of a Cart Price Rule are its own [Extension Attribute](#h.2lcvcwr56aq):
+
+```php
+Magento\SalesRule\Api\Data\ConditionInterface
+```
+
+> Rule Labels of a Cart Price Rule are its own [Extension Attribute](#h.2lcvcwr56aq):
+
+```php
+Magento\SalesRule\Api\Data\RuleLabelInterface
+```
+
+#### ![Magento Section Chevron](./images/icon-chevron.png)Implementing Conditions & Actions Programmatically
+
+> To create a shipping cart rule programmatically, you have to inject \Magento\SalesRule\Model\RuleFactory class:
+
+```php
+<?php
+.....
+
+protected $ruleFactorypublic;
+
+function __construct(
+    \Magento\SalesRule\Model\RuleFactory $ruleFactory,
+
+    \Magento\SalesRule\Api\RuleRepositoryInterface $ruleRepository
+) {
+    $this->rulesFactory = $ruleFactory;
+
+    $this->ruleRepository = $ruleRepository;
+}
+
+```
+
+> And then use it like this:
+
+```php
+<?php
+
+$ruleData = [
+    "name" => "Custom Cart Rule",
+    "description" => "Buy some products and get one more free",
+    "from_date" => null,
+    "to_date" => null,
+    "uses_per_customer" => "0",
+    "is_active" => "1",
+    "stop_rules_processing" => "0",
+    "is_advanced" => "1",
+    "product_ids" => null,
+    "sort_order" => "0",
+    "simple_action" => "buy_x_get_y",
+    "discount_amount" => "1.0000",
+    "discount_qty" = >null,
+    "discount_step" => "3",
+    "apply_to_shipping" => "0",
+    "times_used" => "0",
+    "is_rss" => "1",
+    "coupon_type" => "NO_COUPON",
+    "use_auto_generation" => "0",
+    "uses_per_coupon" => "0",
+    "simple_free_shipping" => "0",
+    "customer_group_ids" => [0, 1, 2, 3],
+    "website_ids" => [1],
+    "coupon_code" => null,
+    "store_labels" => [],
+    "conditions_serialized" => '',
+    "actions_serialized" => ''
+];
+
+$ruleModel = $this->ruleFactory->create();
+$ruleModel->setData($ruleData);
+$this->ruleRepository->save($ruleModel);
+```
+
+
+> Creating conditions and actions for the rule - For the sake of demonstration, let us create the condition that sets a discount for a certain product, if the customer has added more than five items of this product.
+
+```php
+......
+
+protected $ruleFactoryprotected;
+
+protected $productFoundConditionFactory;
+
+protected $productConditionFactory;
+
+public function __construct(
+    \Magento\SalesRule\Model\RuleFactory $ruleFactory,
+    \Magento\SalesRule\Model\Rule\Condition\Product\FoundFactory $productFoundConditionFactory,
+    \Magento\SalesRule\Model\Rule\Condition\ProductFactory $productConditionFactory,
+) {
+    $this->rulesFactory = $ruleFactory;
+    $this->productFoundConditionFactory = $productFoundConditionFactory;
+    $this->productConditionFactory = $productConditionFactory;
+
+
+}
+```
+
+```php
+    $discount = '25';
+    $sku = 'PRODUCT_SKU';
+
+    $shoppingCartPriceRule = $this->rulesFactory->create();
+    $shoppingCartPriceRule->setName('25% off with multiple products - ' . $sku)
+        ->setDescription('Get 25% off with two or more products')
+        ->setFromDate('2000-01-01')
+        ->setToDate(NULL)
+        ->setUsesPerCustomer('0')
+        ->setCustomerGroupIds(array('0', '1', '2', '3',))
+        ->setIsActive('1')
+        ->setStopRulesProcessing('0')
+        ->setIsAdvanced('1')
+        ->setProductIds(NULL)
+        ->setSortOrder('1')
+        ->setSimpleAction('by_percent')
+        ->setDiscountAmount($discount)
+        ->setDiscountQty(NULL)
+        ->setDiscountStep('0')
+        ->setSimpleFreeShipping('0')
+        ->setApplyToShipping('0')
+        ->setTimesUsed('0')
+        ->setIsRss('0')
+        ->setWebsiteIds(array('1',))
+        ->setCouponType('1')
+        ->setCouponCode(NULL)
+        ->setUsesPerCoupon(NULL);
+
+    $productFoundCondition = $this->productFoundConditionFactory->create()
+        ->setType('Magento\SalesRule\Model\Rule\Condition\Product\Found')
+        ->setValue(1) // 1 == FOUND
+        ->setAggregator('all'); // match ALL conditions
+
+    $productCondition = $this->productConditionFactory->create()
+        ->setType('Magento\SalesRule\Model\Rule\Condition\Product')
+        ->setAttribute('sku')
+        ->setOperator('==')
+        ->setValue($sku);
+    $productFoundCondition->addCondition($productCondition);
+
+    $shoppingCartPriceRule->getConditions()->addCondition($productFoundCondition);
+
+    $skuCondition = $this->productConditionFactory->create()
+        ->setType('Magento\SalesRule\Model\Rule\Condition\Product')
+        ->setAttribute('sku')
+        ->setOperator('==')
+        ->setValue($sku);
+    $shoppingCartPriceRule->getActions()->addCondition($skuCondition);
+
+    $qtyCondition = $this->productConditionFactory->create()
+        ->setType('Magento\SalesRule\Model\Rule\Condition\Product')
+        ->setAttribute('quote_item_qty')
+        ->setOperator('>=')
+        ->setValue('2');
+    $shoppingCartPriceRule->getActions()->addCondition($qtyCondition);
+
+    $this->ruleRepository->save($shoppingCartPriceRule);
+```
+
+![Magento Exam Information](./images/icon-info.png)Again, this is just for demonstrative purposes. I think the main thing to remember here is that you use the Factory class: Magento\SalesRule\Model\RuleFactory to create & Magento\SalesRule\Api\RuleRepositoryInterface to save the entity.
+
+![Magento Exam Question](./images/icon-question.png)**What is the difference between sales rules and catalog rules?**
+
+> Compared to [Catalog Price Rules](#h.x0kvcqk03fp8), Sales / [Cart Price Rules](#h.5wkclkkw15ho) are applied to the current user's shopping cart, not to each separate product; they may also require that a certain coupon code is entered to get them. Due to this, the discounts are not visible at the catalog pages, but still allow you to apply different factors for getting them, like the number of products in the customer's shopping cart, their total price, the categories they belong to, and much more. See [Cart Price Rules](#h.5wkclkkw15ho) for a detailed description.
+>
+> Technically here are some differences between [Magento_SalesRule](https://devdocs.magento.com/guides/v2.3/mrg/ce/SalesRule.html&sa=D&ust=1609223265906000&usg=AOvVaw2dSzOItaarn0qrpHSkQMEQ) & [Magento_CatalogRule](https://devdocs.magento.com/guides/v2.3/mrg/ce/CatalogRule.html&sa=D&ust=1609223265906000&usg=AOvVaw1LMCB8f7N6cQqwc903d8d_):
+
+*   Catalog rules update product final price, they are visible in all catalog - category listing, product page.
+*   Cart / Sales Rules are visible only in checkout and can require a coupon.
+*   Cart / Sales Rules can affect shipping price.
+*   Cart / Sales Rules can trigger on products combination.
+
+![Magento Exam Question](./images/icon-question.png)**How do Cart Price Rules impact performance?**
+
+> All calculation happens on the fly in the totals collectors.
+>
+> For each customer, there can be only one active coupon. Rules cannot add other products to the cart and apply to the item they were assigned to work with.
+>
+> Cart rules can slow down the process of adding a product to the cart, as well as checkout and shopping cart pages speed. Performance impact from cart rules can increase in case there is a large number of cart rules with a wide area of application (without connection to website or customer group) and without coupons.
+>
+> Cart Price Rules currently do not have any specific indexes unless you specifically choose Product Attributes as a Condition, then the table: `salesrule_rule_cl` is applied.
+
+![Magento Exam Information](./images/icon-info.png)Currently there are a few core bugs: that impact performance: [Over a certain amount of coupon codes](https://github.com/magento/magento2/pull/20484&sa=D&ust=1609223265910000&usg=AOvVaw3E8S6N3YxvorBdrXZANSDf) or [according to this open issue](https://github.com/magento/magento2/issues/20998&sa=D&ust=1609223265910000&usg=AOvVaw3xuy9uGNJ9Qo2PCdqO5mix).
+
+![Magento Exam Question](./images/icon-question.png)**How are Cart / Sales Price Rules saved?**
+
+![Magento Section Chevron](./images/icon-chevron.png)Cart Price Rules - Repository
+
+> Managing (C.R.U.D actions) Cart Price Rules are done using the [Service Contract](#h.i0qq8aqgijv7) design pattern with the following class:
+
+```php
+Magento\SalesRule\Api\RuleRepositoryInterface::save(
+    \Magento\SalesRule\Api\Data\RuleInterface $rule
+);
+```
+
+
+> Cart Price Coupons are a separate entity managed (C.R.U.D actions) by the following class:
+
+```php
+Magento\SalesRule\Api\CouponRepositoryInterface::save(
+    \Magento\SalesRule\Api\Data\CouponInterface $coupon
+);
+```
+
+> You can also use the following class to generate / remove coupon codes for Cart Price Rules:
+
+```php
+Magento\SalesRule\Api\CouponManagementInterface::generate(
+    \Magento\SalesRule\Api\Data\CouponGenerationSpecInterface $couponSpec
+);
+```
+
+> Rule Conditions of a Cart Price Rule are its own [Extension Attribute](#h.2lcvcwr56aq):
+
+```php
+Magento\SalesRule\Api\Data\ConditionInterface
+```
+
+> Rule Labels of a Cart Price Rule are its own [Extension Attribute](#h.2lcvcwr56aq):
+
+```php
+Magento\SalesRule\Api\Data\RuleLabelInterface
+```
+
+![Magento Exam Question](./images/icon-question.png)**What are the limitations of the native sales rules engine?**
+
+1.  Only one coupon can be applied.
+2.  Getting Conditions, usually the starting conditions are Composite options are processed first.
+3.  Rules cannot add other products to the cart and apply to the item they were assigned to work with.
+
+![Magento Exam Question](./images/icon-question.png)**Describe add-to-cart logic in different scenarios. What is the difference in adding a product to the cart from the product page, from the wishlist, by clicking Reorder, and during quotes merge?**
+
+> Product Page - Add To Cart:
+
+1.  Class: `Magento\Checkout\Controller\Cart\Add`
+2.  Available Methods:
+
+    *  `\Magento\Quote\Model\Quote::addProduct` `$product->getTypeInstance()->prepareForCartAdvanced($request, $product, $processMode);`
+    *  `\Magento\Quote\Model\Quote\Item\Processor::prepare` - `custom_price`
+
+3.  Available events:
+
+    *  `checkout_cart_add_product_complete`
+    *  `checkout_cart_product_add_after`
+    *  `checkout_cart_save_after`
+    *  `sales_quote_product_add_after`
+    *  `sales_quote_add_item`
+    *  `checkout_cart_update_items_before`
+    *  `checkout_cart_update_items_after`
+    *  `checkout_cart_add_product_complete`
+
+4.  Based on the passed product and proper amount of cart model, the corresponding quote item is generated.
+
+
+> Wishlist - Add To Cart:
+
+1.  Available Actions:
+
+    *  `\Magento\Wishlist\Controller\Index\Cart`
+    *  `\Magento\Quote\Model\Quote\Item\Processor::prepare` - `custom_price`
+
+2.  Available events:
+
+    *  `wishlist_product_add_after`
+    *  `wishlist_add_product`
+    *  `checkout_cart_product_add_after`
+    *  `sales_quote_product_add_after`
+    *  `sales_quote_add_item`
+
+
+> Reorder - Add To Cart:
+
+1.  Class: `Magento\Sales\Model\Order\Reorder`
+2.  Available Actions:
+
+    *  `\Magento\Sales\Controller\AbstractController\Reorder`
+    *  `\Magento\Quote\Model\Quote\Item\Processor::prepare` - `custom_price`
+
+3.  Available events:
+
+    *  `checkout_cart_product_add_after`
+    *  `sales_quote_product_add_after`
+    *  `sales_quote_add_item`
+
+
+Quote Merge:
+
+1.  Class: `Magento\Customer\Controller\Account\loginPost`
+2.  Available Methods:
+
+    *  `\Magento\Quote\Model\Quote::merge`
+
+3.  Available events:
+
+    *  `customer_login`
+    *  `load_customer_quote_before`
+    *  `sales_quote_merge_before`
+    *  `sales_quote_add_item`
+    *  `sales_quote_merge_after`
+
+![Magento Exam Question](./images/icon-question.png)**Describe the difference in behavior of different product types in the shopping cart. How are configurable and bundle products rendered?**
+
+> Magento 2 uses renderers to display products in the shopping cart. Each product type (e.g. [Simple](#h.cbgifdse6zd5), [Configurable](#h.98cgcmsgdbu5), [Bundle](#h.41g7zcfrlmri) etc) has a separate renderer Layout Handle + Block class; they are registered in the renderer list with layout instructions as child blocks of the `Magento\Framework\View\Element\RendererList` Block Class under the name `checkout.cart.item.renderers`.
+
+![Magento Exam Information](./images/icon-info.png)The below is a demonstration of how each Product Type / Checkout Module manipulates the shopping cart renderers. You do no have to memorise this, only remember that each product type (e.g. Simple, Configurable, Bundle etc) has a renderer Layout Handle + Block class.
+
+![Magento Section Chevron](./images/icon-chevron.png)[Simple](#h.cbgifdse6zd5) (default)
+
+> [Magento_Checkout](https://devdocs.magento.com/guides/v2.3/mrg/ce/Checkout.html&sa=D&ust=1609223265930000&usg=AOvVaw25sWtEiUCyiT7QCPrSMf3M)::/view/frontend/layout/checkout_cart_item_renderers.xml
+
+
+```xml
+<?xml version="1.0"?>
+<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
+    <update handle="checkout_item_price_renderers"/>
+    <body>
+        <referenceBlock name="checkout.cart.item.renderers">
+            <block class="Magento\Checkout\Block\Cart\Item\Renderer" name="checkout.cart.item.renderers.default" as="default" template="Magento_Checkout::cart/item/default.phtml">
+                <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions" name="checkout.cart.item.renderers.default.actions" as="actions">
+                    <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions\Edit" name="checkout.cart.item.renderers.default.actions.edit" template="Magento_Checkout::cart/item/renderer/actions/edit.phtml"/>
+                    <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions\Remove" name="checkout.cart.item.renderers.default.actions.remove" template="Magento_Checkout::cart/item/renderer/actions/remove.phtml"/>
+                </block>
+            </block>
+            <block class="Magento\Checkout\Block\Cart\Item\Renderer" name="checkout.cart.item.renderers.simple" as="simple" template="Magento_Checkout::cart/item/default.phtml">
+                <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions" name="checkout.cart.item.renderers.simple.actions" as="actions">
+                    <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions\Edit" name="checkout.cart.item.renderers.simple.actions.edit" template="Magento_Checkout::cart/item/renderer/actions/edit.phtml"/>
+                    <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions\Remove" name="checkout.cart.item.renderers.simple.actions.remove" template="Magento_Checkout::cart/item/renderer/actions/remove.phtml"/>
+                </block>
+            </block>
+        </referenceBlock>
+    </body>
+</page>
+```
+
+![Magento Exam Information](./images/icon-info.png)`Magento\Checkout\Block\Cart\Item\Renderer`
+
+![Magento Section Chevron](./images/icon-chevron.png)[Configurable](#h.98cgcmsgdbu5)
+
+> [Magento_ConfigurableProduct](https://devdocs.magento.com/guides/v2.3/mrg/ce/ConfigurableProduct.html&sa=D&ust=1609223265932000&usg=AOvVaw0MjLhCpRxV0E9sxt4IM8RK)::/view/frontend/layout/checkout_cart_item_renderers.xml
+
+```xml
+<?xml version="1.0"?>
+<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
+    <body>
+        <referenceBlock name="checkout.cart.item.renderers">
+            <block class="Magento\ConfigurableProduct\Block\Cart\Item\Renderer\Configurable" name="checkout.cart.item.renderers.configurable" as="configurable" template="Magento_Checkout::cart/item/default.phtml">
+                <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions" name="checkout.cart.item.renderers.configurable.actions" as="actions">
+                    <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions\Edit" name="checkout.cart.item.renderers.configurable.actions.edit" template="Magento_Checkout::cart/item/renderer/actions/edit.phtml"/>
+                    <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions\Remove" name="checkout.cart.item.renderers.configurable.actions.remove" template="Magento_Checkout::cart/item/renderer/actions/remove.phtml"/>
+                </block>
+            </block>
+        </referenceBlock>
+    </body>
+</page>
+```
+
+![Magento Exam Information](./images/icon-info.png)`Magento\ConfigurableProduct\Block\Cart\Item\Renderer\Configurable`
+
+![Magento Section Chevron](./images/icon-chevron.png)[Virtual](#h.t3fkw0wf3trp)
+
+> Magento_Catalog::/view/frontend/layout/checkout_cart_item_renderers.xml
+
+```xml
+<?xml version="1.0"?>
+<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
+    <body>
+        <referenceBlock name="checkout.cart.item.renderers">
+            <block class="Magento\Checkout\Block\Cart\Item\Renderer" name="checkout.cart.item.renderers.virtual" as="virtual" template="Magento_Checkout::cart/item/default.phtml">
+                <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions" name="checkout.cart.item.renderers.virtual.actions" as="actions">
+                    <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions\Edit" name="checkout.cart.item.renderers.virtual.actions.edit" template="Magento_Checkout::cart/item/renderer/actions/edit.phtml"/>
+                    <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions\Remove" name="checkout.cart.item.renderers.virtual.actions.remove" template="Magento_Checkout::cart/item/renderer/actions/remove.phtml"/>
+                </block>
+            </block>
+        </referenceBlock>
+    </body>
+</page>
+```
+
+![Magento Exam Information](./images/icon-info.png)Magento\Checkout\Block\Cart\Item\Renderer
+
+![Magento Section Chevron](./images/icon-chevron.png)[Bundle](#h.41g7zcfrlmri)
+
+> [Magento_Bundle](https://devdocs.magento.com/guides/v2.3/mrg/ce/Bundle.html&sa=D&ust=1609223265935000&usg=AOvVaw3pnbLTvlOuHR2SakF0u6_0)::/view/frontend/layout/checkout_cart_item_renderers.xml
+
+```xml
+<?xml version="1.0"?>
+<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
+    <body>
+        <referenceBlock name="checkout.cart.item.renderers">
+            <block class="Magento\Bundle\Block\Checkout\Cart\Item\Renderer" name="checkout.cart.item.renderers.bundle" as="bundle" template="Magento_Checkout::cart/item/default.phtml">
+                <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions" name="checkout.cart.item.renderers.bundle.actions" as="actions">
+                    <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions\Edit" name="checkout.cart.item.renderers.bundle.actions.edit" template="Magento_Checkout::cart/item/renderer/actions/edit.phtml"/>
+                    <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions\Remove" name="checkout.cart.item.renderers.bundle.actions.remove" template="Magento_Checkout::cart/item/renderer/actions/remove.phtml"/>
+                </block>
+            </block>
+        </referenceBlock>
+    </body>
+</page>
+```
+
+![Magento Exam Information](./images/icon-info.png)Magento\Bundle\Block\Checkout\Cart\Item\Renderer
+
+![Magento Section Chevron](./images/icon-chevron.png)[Downloadable](#h.614rvm49j6y9)
+
+[Magento_Downloadable](https://devdocs.magento.com/guides/v2.3/mrg/ce/Downloadable.html&sa=D&ust=1609223265937000&usg=AOvVaw131smzZ84x0p1Ieqg1JZou)::/view/frontend/layout/checkout_cart_item_renderers.xml
+
+```xml
+<?xml version="1.0"?>
+<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
+    <body>
+        <referenceBlock name="checkout.cart.item.renderers">
+            <block class="Magento\Downloadable\Block\Checkout\Cart\Item\Renderer" name="checkout.cart.item.renderers.downloadable" as="downloadable" template="Magento_Checkout::cart/item/default.phtml">
+                <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions" name="checkout.cart.item.renderers.downloadable.actions" as="actions">
+                    <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions\Edit" name="checkout.cart.item.renderers.downloadable.actions.edit" template="Magento_Checkout::cart/item/renderer/actions/edit.phtml"/>
+                    <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions\Remove" name="checkout.cart.item.renderers.downloadable.actions.remove" template="Magento_Checkout::cart/item/renderer/actions/remove.phtml"/>
+                </block>
+            </block>
+        </referenceBlock>
+    </body>
+</page>
+```
+
+![Magento Exam Information](./images/icon-info.png)Magento\Downloadable\Block\Checkout\Cart\Item\Renderer
+
+![Magento Section Chevron](./images/icon-chevron.png)[Grouped Product](#h.cbgifdse6zd5)
+
+[Magento_GroupedProduct](https://devdocs.magento.com/guides/v2.3/mrg/ce/GroupedProduct.html&sa=D&ust=1609223265939000&usg=AOvVaw2ak01jrqeQtGkMgcKZVKXR)::/view/frontend/layout/checkout_cart_item_renderers.xml
+
+```xml
+<?xml version="1.0"?>
+<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
+    <body>
+        <referenceBlock name="checkout.cart.item.renderers">
+            <block class="Magento\GroupedProduct\Block\Cart\Item\Renderer\Grouped" name="checkout.cart.item.renderers.grouped" as="grouped" template="Magento_Checkout::cart/item/default.phtml">
+                <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions" name="checkout.cart.item.renderers.grouped.actions" as="actions">
+                    <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions\Edit" name="checkout.cart.item.renderers.grouped.actions.edit" template="Magento_Checkout::cart/item/renderer/actions/edit.phtml"/>
+                    <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions\Remove" name="checkout.cart.item.renderers.grouped.actions.remove" template="Magento_Checkout::cart/item/renderer/actions/remove.phtml"/>
+                </block>
+            </block>
+        </referenceBlock>
+    </body>
+</page>
+```
+
+![Magento Exam Information](./images/icon-info.png)Magento\GroupedProduct\Block\Cart\Item\Renderer\Grouped
+
+![Magento Section Chevron](./images/icon-chevron.png)[Wishlist](https://docs.magento.com/user-guide/customers/account-dashboard-my-wish-list.html&sa=D&ust=1609223265942000&usg=AOvVaw2kLxv2DoN5McuSyxFPHEDF)
+
+[Magento_Wishlist](https://devdocs.magento.com/guides/v2.3/mrg/ce/Wishlist.html&sa=D&ust=1609223265942000&usg=AOvVaw3QekxPHSAFYl8cIus4Ds3G)::view/frontend/layout/checkout_cart_item_renderers.xml
+
+```xml
+<?xml version="1.0"?>
+<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
+    <body>
+        <referenceBlock name="checkout.cart.item.renderers.default.actions">
+            <block class="Magento\Wishlist\Block\Cart\Item\Renderer\Actions\MoveToWishlist" name="checkout.cart.item.renderers.default.actions.move_to_wishlist" template="Magento_Wishlist::cart/item/renderer/actions/move_to_wishlist.phtml" before="checkout.cart.item.renderers.default.actions.edit"/>
+        </referenceBlock>
+        <referenceBlock name="checkout.cart.item.renderers.simple.actions">
+            <block class="Magento\Wishlist\Block\Cart\Item\Renderer\Actions\MoveToWishlist" name="checkout.cart.item.renderers.simple.actions.move_to_wishlist" template="Magento_Wishlist::cart/item/renderer/actions/move_to_wishlist.phtml" before="checkout.cart.item.renderers.simple.actions.edit"/>
+        </referenceBlock>
+        <referenceBlock name="checkout.cart.item.renderers.bundle.actions">
+            <block class="Magento\Wishlist\Block\Cart\Item\Renderer\Actions\MoveToWishlist" name="checkout.cart.item.renderers.bundle.actions.move_to_wishlist" template="Magento_Wishlist::cart/item/renderer/actions/move_to_wishlist.phtml" before="checkout.cart.item.renderers.bundle.actions.edit"/>
+        </referenceBlock>
+        <referenceBlock name="checkout.cart.item.renderers.downloadable.actions">
+            <block class="Magento\Wishlist\Block\Cart\Item\Renderer\Actions\MoveToWishlist" name="checkout.cart.item.renderers.downloadable.actions.move_to_wishlist" template="Magento_Wishlist::cart/item/renderer/actions/move_to_wishlist.phtml" before="checkout.cart.item.renderers.downloadable.actions.edit"/>
+        </referenceBlock>
+        <referenceBlock name="checkout.cart.item.renderers.grouped.actions">
+            <block class="Magento\Wishlist\Block\Cart\Item\Renderer\Actions\MoveToWishlist" name="checkout.cart.item.renderers.grouped.actions.move_to_wishlist" template="Magento_Wishlist::cart/item/renderer/actions/move_to_wishlist.phtml" before="checkout.cart.item.renderers.grouped.actions.edit"/>
+        </referenceBlock>
+        <referenceBlock name="checkout.cart.item.renderers.configurable.actions">
+            <block class="Magento\Wishlist\Block\Cart\Item\Renderer\Actions\MoveToWishlist" name="checkout.cart.item.renderers.configurable.actions.move_to_wishlist" template="Magento_Wishlist::cart/item/renderer/actions/move_to_wishlist.phtml" before="checkout.cart.item.renderers.configurable.actions.edit"/>
+        </referenceBlock>
+        <referenceBlock name="checkout.cart.item.renderers.virtual.actions">
+            <block class="Magento\Wishlist\Block\Cart\Item\Renderer\Actions\MoveToWishlist" name="checkout.cart.item.renderers.virtual.actions.move_to_wishlist" template="Magento_Wishlist::cart/item/renderer/actions/move_to_wishlist.phtml" before="checkout.cart.item.renderers.virtual.actions.edit"/>
+        </referenceBlock>
+    </body>
+</page>
+```
+
+![Magento Exam Information](./images/icon-info.png)Changes the default Block class per product type.
+
+![Magento Section Chevron](./images/icon-chevron.png)Multiple Wishlists (Magento Commerce / Enterprise edition only)
+
+> [Magento_MultipleWishlist](https://devdocs.magento.com/guides/v2.3/mrg/ee/MultipleWishlist.html&sa=D&ust=1609223265946000&usg=AOvVaw3wcaWUGElF689Vzj2b_G7l)::/view/frontend/layout/checkout_cart_item_renderers.xml
+
+```xml
+<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
+    <body>
+        <referenceBlock name="checkout.cart.item.renderers.gift-card.actions">
+            <block class="Magento\Wishlist\Block\Cart\Item\Renderer\Actions\MoveToWishlist" name="checkout.cart.item.renderers.giftcard.actions.move_to_wishlist" template="Magento_Wishlist::cart/item/renderer/actions/move_to_wishlist.phtml" before="checkout.cart.item.renderers.giftcard.actions.edit"/>
+        </referenceBlock>
+    </body>
+</page>
+```
+
+![Magento Exam Information](./images/icon-info.png)Magento\Wishlist\Block\Cart\Item\Renderer\Actions\MoveToWishlist
+
+![Magento Section Chevron](./images/icon-chevron.png)Magento Advanced Checkout (Magento Commerce / Enterprise edition only)
+
+> [Magento_AdvancedCheckout](https://devdocs.magento.com/guides/v2.3/mrg/ee/AdvancedCheckout.html&sa=D&ust=1609223265947000&usg=AOvVaw2Auj3jlpVQl1bI97PWWJ9B)/view/frontend/layout/checkout_cart_item_renderers.xml
+
+```xml
+<?xml version="1.0"?>
+<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
+    <body>
+        <referenceBlock name="checkout.cart.item.renderers">
+            <block class="Magento\Checkout\Block\Cart\Item\Renderer" name="checkout.cart.item.renderers.undefined" as="undefined"/>
+        </referenceBlock>
+    </body>
+</page>
+```
+
+![Magento Exam Information](./images/icon-info.png)This looks undefined currently. A work in progress.
+
+![Magento Section Chevron](./images/icon-chevron.png)[Giftcard](#h.87l1vab27p5t) (Magento Commerce / Enterprise edition only)
+
+> [Magento_GiftCard](https://devdocs.magento.com/guides/v2.3/mrg/ee/GiftCard.html&sa=D&ust=1609223265948000&usg=AOvVaw3IddNz0q1mpk7Q0c54DFG5)::/view/frontend/layout/checkout_cart_item_renderers.xml
+
+```xml
+<?xml version="1.0"?>
+<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
+    <body>
+        <referenceBlock name="checkout.cart.item.renderers">
+            <block class="Magento\GiftCard\Block\Checkout\Cart\Item\Renderer" name="checkout.cart.item.renderers.giftcard" as="giftcard" template="Magento_Checkout::cart/item/default.phtml">
+                <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions" name="checkout.cart.item.renderers.gift-card.actions" as="actions">
+                    <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions\Edit" name="checkout.cart.item.renderers.giftcard.actions.edit" template="Magento_Checkout::cart/item/renderer/actions/edit.phtml"/>
+                    <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions\Remove" name="checkout.cart.item.renderers.giftcard.actions.remove" template="Magento_Checkout::cart/item/renderer/actions/remove.phtml"/>
+                </block>
+            </block>
+        </referenceBlock>
+    </body>
+</page>
+```
+
+![Magento Exam Information](./images/icon-info.png)Magento\GiftCard\Block\Checkout\Cart\Item\Renderer
+
+![Magento Section Chevron](./images/icon-chevron.png)[Gift Options](https://docs.magento.com/user-guide/sales/gift-options.html&sa=D&ust=1609223265949000&usg=AOvVaw3q1MMW-7rBzpCGuoDZdD4l) (Magento Commerce / Enterprise edition only)
+
+> [Magento_GiftMessage](https://devdocs.magento.com/guides/v2.3/mrg/ce/GiftMessage.html&sa=D&ust=1609223265950000&usg=AOvVaw03UKWI59ObQLtaubhrdno4)::view/frontend/layout/checkout_cart_item_renderers.xml
+
+```xml
+<?xml version="1.0"?>
+<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
+    <body>
+        <referenceBlock name="checkout.cart.item.renderers.default.actions">
+            <block class="Magento\GiftMessage\Block\Cart\Item\Renderer\Actions\GiftOptions" name="checkout.cart.item.renderers.default.actions.gift_options" template="Magento_GiftMessage::cart/item/renderer/actions/gift_options.phtml" before="-" cacheable="false">
+                <arguments>
+                    <argument name="jsLayout" xsi:type="array">
+                        <item name="types" xsi:type="array"/>
+                        <item name="components" xsi:type="array">
+                            <item name="giftOptionsCartItem" xsi:type="array">
+                                <item name="component" xsi:type="string">Magento_GiftMessage/js/view/gift-message</item>
+                                <item name="config" xsi:type="array">
+                                    <item name="template" xsi:type="string">Magento_GiftMessage/gift-message-item-level</item>
+                                    <item name="formTemplate" xsi:type="string">Magento_GiftMessage/gift-message-form</item>
+                                </item>
+                            </item>
+                        </item>
+                    </argument>
+                </arguments>
+            </block>
+        </referenceBlock>
+        <referenceBlock name="checkout.cart.item.renderers.simple.actions">
+            <block class="Magento\GiftMessage\Block\Cart\Item\Renderer\Actions\GiftOptions" name="checkout.cart.item.renderers.simple.actions.gift_options" template="Magento_GiftMessage::cart/item/renderer/actions/gift_options.phtml" before="-" cacheable="false">
+                <arguments>
+                    <argument name="jsLayout" xsi:type="array">
+                        <item name="types" xsi:type="array"/>
+                        <item name="components" xsi:type="array">
+                            <item name="giftOptionsCartItem" xsi:type="array">
+                                <item name="component" xsi:type="string">Magento_GiftMessage/js/view/gift-message</item>
+                                <item name="config" xsi:type="array">
+                                    <item name="template" xsi:type="string">Magento_GiftMessage/gift-message-item-level</item>
+                                    <item name="formTemplate" xsi:type="string">Magento_GiftMessage/gift-message-form</item>
+                                </item>
+                            </item>
+                        </item>
+                    </argument>
+                </arguments>
+            </block>
+        </referenceBlock>
+        <referenceBlock name="checkout.cart.item.renderers.bundle.actions">
+            <block class="Magento\GiftMessage\Block\Cart\Item\Renderer\Actions\GiftOptions" name="checkout.cart.item.renderers.bundle.actions.gift_options" template="Magento_GiftMessage::cart/item/renderer/actions/gift_options.phtml" before="-" cacheable="false">
+                <arguments>
+                    <argument name="jsLayout" xsi:type="array">
+                        <item name="types" xsi:type="array"/>
+                        <item name="components" xsi:type="array">
+                            <item name="giftOptionsCartItem" xsi:type="array">
+                                <item name="component" xsi:type="string">Magento_GiftMessage/js/view/gift-message</item>
+                                <item name="config" xsi:type="array">
+                                    <item name="template" xsi:type="string">Magento_GiftMessage/gift-message-item-level</item>
+                                    <item name="formTemplate" xsi:type="string">Magento_GiftMessage/gift-message-form</item>
+                                </item>
+                            </item>
+                        </item>
+                    </argument>
+                </arguments>
+            </block>
+        </referenceBlock>
+        <referenceBlock name="checkout.cart.item.renderers.grouped.actions">
+            <block class="Magento\GiftMessage\Block\Cart\Item\Renderer\Actions\GiftOptions" name="checkout.cart.item.renderers.grouped.actions.gift_options" template="Magento_GiftMessage::cart/item/renderer/actions/gift_options.phtml" before="-" cacheable="false">
+                <arguments>
+                    <argument name="jsLayout" xsi:type="array">
+                        <item name="types" xsi:type="array"/>
+                        <item name="components" xsi:type="array">
+                            <item name="giftOptionsCartItem" xsi:type="array">
+                                <item name="component" xsi:type="string">Magento_GiftMessage/js/view/gift-message</item>
+                                <item name="config" xsi:type="array">
+                                    <item name="template" xsi:type="string">Magento_GiftMessage/gift-message-item-level</item>
+                                    <item name="formTemplate" xsi:type="string">Magento_GiftMessage/gift-message-form</item>
+                                </item>
+                            </item>
+                        </item>
+                    </argument>
+                </arguments>
+            </block>
+        </referenceBlock>
+        <referenceBlock name="checkout.cart.item.renderers.configurable.actions">
+            <block class="Magento\GiftMessage\Block\Cart\Item\Renderer\Actions\GiftOptions" name="checkout.cart.item.renderers.configurable.actions.gift_options" template="Magento_GiftMessage::cart/item/renderer/actions/gift_options.phtml" before="-" cacheable="false">
+                <arguments>
+                    <argument name="jsLayout" xsi:type="array">
+                        <item name="types" xsi:type="array"/>
+                        <item name="components" xsi:type="array">
+                            <item name="giftOptionsCartItem" xsi:type="array">
+                                <item name="component" xsi:type="string">Magento_GiftMessage/js/view/gift-message</item>
+                                <item name="config" xsi:type="array">
+                                    <item name="template" xsi:type="string">Magento_GiftMessage/gift-message-item-level</item>
+                                    <item name="formTemplate" xsi:type="string">Magento_GiftMessage/gift-message-form</item>
+                                </item>
+                            </item>
+                        </item>
+                    </argument>
+                </arguments>
+            </block>
+        </referenceBlock>
+        <referenceBlock name="checkout.cart.item.renderers.gift-card.actions">
+            <block class="Magento\GiftMessage\Block\Cart\Item\Renderer\Actions\GiftOptions" name="checkout.cart.item.renderers.gift-card.actions.gift_options" template="Magento_GiftMessage::cart/item/renderer/actions/gift_options.phtml" before="-" cacheable="false">
+                <arguments>
+                    <argument name="jsLayout" xsi:type="array">
+                        <item name="types" xsi:type="array"/>
+                        <item name="components" xsi:type="array">
+                            <item name="giftOptionsCartItem" xsi:type="array">
+                                <item name="component" xsi:type="string">Magento_GiftMessage/js/view/gift-message</item>
+                                <item name="config" xsi:type="array">
+                                    <item name="template" xsi:type="string">Magento_GiftMessage/gift-message-item-level</item>
+                                    <item name="formTemplate" xsi:type="string">Magento_GiftMessage/gift-message-form</item>
+                                </item>
+                            </item>
+                        </item>
+                    </argument>
+                </arguments>
+            </block>
+        </referenceBlock>
+    </body>
+</page>
+```
+
+![Magento Exam Information](./images/icon-info.png)Looks like Gift Options overwrites the main renders to add it's functionality.
+
+![Magento Section Chevron](./images/icon-chevron.png)[Gift Wrap](https://docs.magento.com/user-guide/sales/gift-wrap.html&sa=D&ust=1609223265958000&usg=AOvVaw0Oq9nGFFhmVe1vhxXVIUt_) (Magento Commerce / Enterprise edition only)
+
+> [Magento_GiftWrapping](https://devdocs.magento.com/guides/v2.3/mrg/ee/GiftWrapping.html&sa=D&ust=1609223265958000&usg=AOvVaw0w1lgGVZ8qz4HaxkM-EZtu)::view/frontend/layout/checkout_cart_item_renderers.xml
+
+```xml
+<?xml version="1.0"?>
+<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
+    <body>
+        <referenceBlock name="checkout.cart.item.renderers.simple.actions.gift_options">
+            <arguments>
+                <argument name="jsLayout" xsi:type="array">
+                    <item name="types" xsi:type="array"/>
+                    <item name="components" xsi:type="array">
+                        <item name="giftOptionsCartItem" xsi:type="array">
+                            <item name="children" xsi:type="array">
+                                <item name="giftWrapping" xsi:type="array">
+                                    <item name="component" xsi:type="string">Magento_GiftWrapping/js/view/gift-wrapping</item>
+                                    <item name="config" xsi:type="array">
+                                        <item name="template" xsi:type="string">Magento_GiftWrapping/gift-wrapping</item>
+                                        <item name="appliedTemplate" xsi:type="string">Magento_GiftWrapping/applied</item>
+                                    </item>
+                                </item>
+                            </item>
+                        </item>
+                    </item>
+                </argument>
+            </arguments>
+        </referenceBlock>
+        <referenceBlock name="checkout.cart.item.renderers.default.actions.gift_options">
+            <arguments>
+                <argument name="jsLayout" xsi:type="array">
+                    <item name="types" xsi:type="array"/>
+                    <item name="components" xsi:type="array">
+                        <item name="giftOptionsCartItem" xsi:type="array">
+                            <item name="children" xsi:type="array">
+                                <item name="giftWrapping" xsi:type="array">
+                                    <item name="component" xsi:type="string">Magento_GiftWrapping/js/view/gift-wrapping</item>
+                                    <item name="config" xsi:type="array">
+                                        <item name="template" xsi:type="string">Magento_GiftWrapping/gift-wrapping</item>
+                                        <item name="appliedTemplate" xsi:type="string">Magento_GiftWrapping/applied</item>
+                                    </item>
+                                </item>
+                            </item>
+                        </item>
+                    </item>
+                </argument>
+            </arguments>
+        </referenceBlock>
+        <referenceBlock name="checkout.cart.item.renderers.bundle.actions.gift_options">
+            <arguments>
+                <argument name="jsLayout" xsi:type="array">
+                    <item name="types" xsi:type="array"/>
+                    <item name="components" xsi:type="array">
+                        <item name="giftOptionsCartItem" xsi:type="array">
+                            <item name="children" xsi:type="array">
+                                <item name="giftWrapping" xsi:type="array">
+                                    <item name="component" xsi:type="string">Magento_GiftWrapping/js/view/gift-wrapping</item>
+                                    <item name="config" xsi:type="array">
+                                        <item name="template" xsi:type="string">Magento_GiftWrapping/gift-wrapping</item>
+                                        <item name="appliedTemplate" xsi:type="string">Magento_GiftWrapping/applied</item>
+                                    </item>
+                                </item>
+                            </item>
+                        </item>
+                    </item>
+                </argument>
+            </arguments>
+        </referenceBlock>
+        <referenceBlock name="checkout.cart.item.renderers.configurable.actions.gift_options">
+            <arguments>
+                <argument name="jsLayout" xsi:type="array">
+                    <item name="types" xsi:type="array"/>
+                    <item name="components" xsi:type="array">
+                        <item name="giftOptionsCartItem" xsi:type="array">
+                            <item name="children" xsi:type="array">
+                                <item name="giftWrapping" xsi:type="array">
+                                    <item name="component" xsi:type="string">Magento_GiftWrapping/js/view/gift-wrapping</item>
+                                    <item name="config" xsi:type="array">
+                                        <item name="template" xsi:type="string">Magento_GiftWrapping/gift-wrapping</item>
+                                        <item name="appliedTemplate" xsi:type="string">Magento_GiftWrapping/applied</item>
+                                    </item>
+                                </item>
+                            </item>
+                        </item>
+                    </item>
+                </argument>
+            </arguments>
+        </referenceBlock>
+        <referenceBlock name="checkout.cart.item.renderers.giftcard.actions.gift_options">
+            <arguments>
+                <argument name="jsLayout" xsi:type="array">
+                    <item name="types" xsi:type="array"/>
+                    <item name="components" xsi:type="array">
+                        <item name="giftOptionsCartItem" xsi:type="array">
+                            <item name="children" xsi:type="array">
+                                <item name="giftWrapping" xsi:type="array">
+                                    <item name="component" xsi:type="string">Magento_GiftWrapping/js/view/gift-wrapping</item>
+                                    <item name="config" xsi:type="array">
+                                        <item name="template" xsi:type="string">Magento_GiftWrapping/gift-wrapping</item>
+                                        <item name="appliedTemplate" xsi:type="string">Magento_GiftWrapping/applied</item>
+                                    </item>
+                                </item>
+                            </item>
+                        </item>
+                    </item>
+                </argument>
+            </arguments>
+        </referenceBlock>
+        <referenceBlock name="checkout.cart.item.renderers.grouped.actions.gift_options">
+            <arguments>
+                <argument name="jsLayout" xsi:type="array">
+                    <item name="types" xsi:type="array"/>
+                    <item name="components" xsi:type="array">
+                        <item name="giftOptionsCartItem" xsi:type="array">
+                            <item name="children" xsi:type="array">
+                                <item name="giftWrapping" xsi:type="array">
+                                    <item name="component" xsi:type="string">Magento_GiftWrapping/js/view/gift-wrapping</item>
+                                    <item name="config" xsi:type="array">
+                                        <item name="template" xsi:type="string">Magento_GiftWrapping/gift-wrapping</item>
+                                        <item name="appliedTemplate" xsi:type="string">Magento_GiftWrapping/applied</item>
+                                    </item>
+                                </item>
+                            </item>
+                        </item>
+                    </item>
+                </argument>
+            </arguments>
+        </referenceBlock>
+    </body>
+</page>
+```
+
+![Magento Exam Information](./images/icon-info.png)Looks like Gift Wrap overwrites the main renders to add it's functionality.
+
+![Magento Exam Question](./images/icon-question.png)**How can you create a custom shopping cart renderer?**
+
+> Firstly, following Block class is responsible for rendering the Cart/Quote Item HTML:
+
+```php
+\Magento\Checkout\Block\Cart\AbstractCart::getItemHtml()
+```
+
+> Therefore, the product will be available in the template of our block by calling: `$cartItem = $block->getItem();`
+>
+> Code below:
+
+```php
+public function getItemHtml(\Magento\Quote\Model\Quote\Item $item)
+{
+    $renderer = $this->getItemRenderer($item->getProductType())->setItem($item);
+    return $renderer->toHtml();
+}
+```
+
+> Next, we need to create a Block, `MyVendor\MyModule\Block\Cart\CustomRenderer` for example, that will be responsible for html content of a product. This block extends class
+
+```php
+Magento\Checkout\Block\Cart\Item\Renderer
+```
+
+> Finally, we need to create a `checkout_cart_item_renderers.xml` layout handle. Afterwards, all the "custom-type" type products will use our class for display.
+
+`<module_dir>/view/frontend/layout/checkout_cart_item_renderers.xml`
+```xml
+<?xml version="1.0"?>
+<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
+    <body>
+        <referenceBlock name="checkout.cart.item.renderers">
+            <block class="MyVendor\MyModule\Block\Cart\CustomRenderer" as="custom-type" template="Magento_Checkout::cart/item/default.phtml">
+                <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions" name="checkout.cart.item.renderers.custom.actions" as="actions">
+                    <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions\Edit" name="checkout.cart.item.renderers.custom.actions.edit" template="Magento_Checkout::cart/item/renderer/actions/edit.phtml"/>
+                    <block class="Magento\Checkout\Block\Cart\Item\Renderer\Actions\Remove" name="checkout.cart.item.renderers.custom.actions.remove" template="Magento_Checkout::cart/item/renderer/actions/remove.phtml"/>
+                </block>
+            </block>
+        </referenceBlock>
+    </body>
+</page>
+```
+![Magento Exam Question](./images/icon-question.png)**How can you customize cart edit functionality?**
+
+1. Create a [Preference](#h.9ofwnl5q9fnf) or [Plugin Interceptor](#h.nc1ow1wmf2km) for the following action class: `Magento\Checkout\Controller\Cart\Configure` - Which, in its turn, allows the user to edit the product, already added to the shopping cart.
+2. Depending on your needs, you can modify either the action or the corresponding layout / templates in `checkout_cart_index.xml`
+
+![Magento Exam Question](./images/icon-question.png)**How would you create an extension that deletes one item if another was deleted?**
+
+> Using the an [Observer](#h.y2lezqicnwxl) on event: `sales_quote_remove_item`
+
+```php
+<?php
+
+/**
+ * @see Event: sales_quote_remove_item
+ */
+
+namespace MyVendor\MyModule\Observer;
+
+use Magento\Framework\Event\Observer;
+use Magento\Framework\Event\ObserverInterface;
+
+class SalesQuoteRemoveItemObserver implements ObserverInterface
+{
+    public function execute(Observer $observer)
+    {
+        $deletedItem = $observer->getQuoteItem();
+        // We can also check the ID or SKU of the deleted cart item, and depending on the result, delete the other one.
+    }
+}
+
+```
+
+![Magento Exam Question](./images/icon-question.png)**How do you add a field to the shipping address?**
+
+> You can add new fields to default checkout forms, such as shipping address or billing address forms. To illustrate this ability, this topic describes adding a field to the shipping address form.
+>
+> To add your custom field to the checkout address form and access its value on the client side:
+
+1.  Add the field to the Layout Processor.
+2.  Add a JS mixin to modify data submission.
+3.  Load your mixin.
+4.  Add the field to the address model.
+5.  Access the value of the custom field on the server side.
+
+![Magento Exam Information](./images/icon-info.png)The below is a [copy for the following guide](https://devdocs.magento.com/guides/v2.3/howdoi/checkout/checkout_new_field.html&sa=D&ust=1609223265982000&usg=AOvVaw0QeygeMkrRyOtY-NsRcJhs), this is for demonstration purposes only. Main things to remember are the above steps.
+
+![Magento Section Chevron](./images/icon-chevron.png) Step 1: Add the field to the Layout Processor
+
+> Both shipping address and billing address forms are generated dynamically.
+>
+> To modify their layouts, create a [Plugin Interceptor](#h.nc1ow1wmf2km) for the method:
+>
+> `Magento\Checkout\Block\Checkout\LayoutProcessor::process`
+>
+> Declare it in the di.xml file in your module.
+>
+> The following code snippet enumerates sample logic for adding a field named Custom Attribute to the shipping address form:
+
+```php
+<?php
+$customAttributeCode = 'custom_field';
+$customField = [
+    'component' => 'Magento_Ui/js/form/element/abstract',
+    'config' => [ // customScope is used to group elements within a single form (e.g. they can be validated separately) 'customScope' => 'shippingAddress.custom_attributes',
+        'customEntry' => null,
+        'template' => 'ui/form/field',
+        'elementTmpl' => 'ui/form/element/input',
+        'tooltip' => [
+            'description' => 'this is what the field is for',
+        ],
+    ],
+    'dataScope' => 'shippingAddress.custom_attributes' . '.' . $customAttributeCode,
+    'label' => 'Custom Attribute',
+    'provider' => 'checkoutProvider',
+    'sortOrder' => 0,
+    'validation' => [
+        'required-entry' => true
+    ],
+    'options' => [],
+    'filterBy' => null,
+    'customEntry' => null,
+    'visible' => true,
+    'value' => '' // value field is used to set a default value of the attribute
+];
+
+$jsLayout['components']['checkout']['children']['steps']['children']['shipping-step']['children']['shippingAddress']['children']['shipping-address-fieldset']['children'][$customAttributeCode] = $customField;
+```
+
+> Via the previous example, the field is added to the customAttributes property of `Magento_Checkout/js/model/new-customer-address.js`, a JavaScript object that lists all predefined address attributes and matches the corresponding server-side interface `Magento\Quote\Api\Data\AddressInterface`.
+>
+> The customAttributes property was designed to contain custom EAV address attributes and is related to the `Magento\Quote\Model\Quote\Address\CustomAttributeListInterface::getAttributes` method. The sample code above will automatically handle local storage persistence on the frontend.
+>
+> Alternatively
+>
+> Instead of adding a plugin, you can use a [Dependency Injection](#h.9ofwnl5q9fnf) (DI). To use a DI, add the LayoutProcessor, which adds the custom field to the address form class, to the `<module_dir>/Block/Checkout/` directory. The class must implement the interface:
+>
+> `\Magento\Checkout\Block\Checkout\LayoutProcessorInterface`
+>
+> Use the code sample above as an example of the `\Magento\Checkout\Block\Checkout\LayoutProcessorInterface::process()` method implementation.
+>
+> To add your LayoutProcessor class the corresponding pool of processors, specify the following (where %unique_name% and %path\to\your\LayoutProcessor% must be replaced by your real values) in the `<module_dir>/etc/frontend/di.xml` file:
+
+```xml
+<type name="Magento\Checkout\Block\Onepage">
+    <arguments>
+        <argument name="layoutProcessors" xsi:type="array">
+            <item name="%unique_name%" xsi:type="object">%path\to\your\LayoutProcessor%</item>
+        </argument>
+    </arguments>
+</type>
+```
+
+![Magento Section Chevron](./images/icon-chevron.png) Step 2: Add a JS mixin to modify data submission
+
+> Add a [JSComponent](#h.kg229a1fn1nm) [Mixin](https://magento.stackexchange.com/a/210392/24588&sa=D&ust=1609223265987000&usg=AOvVaw2VhmcibKg1vOLX1h42-YwK), to the server side, to change the behavior of the component responsible for the data submission.
+>
+> In your custom module, define a mixin as a separate AMD module that returns a callback function. Add the mixin file anywhere in the `<module_dir>/view/frontend/web` directory. There are no strict requirements for the mixin file naming.
+>
+> The following code sample is a sample mixin modifying the behavior of the component:
+>
+> `Magento_Checkout/js/action/set-shipping-information`
+>
+> the component responsible for data submission between shipping and billing checkout steps:
+
+
+```js
+/*jshint browser:true jquery:true*/
+/*global alert*/
+define(
+    [
+        'jquery',
+        'mage/utils/wrapper',
+        'Magento_Checkout/js/model/quote'
+    ],
+    function (
+        $,
+        wrapper,
+        quote
+    ) {
+        'use strict';
+
+        return function (setShippingInformationAction) {
+
+            return wrapper.wrap(setShippingInformationAction, function (originalAction) {
+
+                var shippingAddress = quote.shippingAddress();
+                if (shippingAddress['extension_attributes'] === undefined) {
+                    shippingAddress['extension_attributes'] = {};
+                }
+
+                shippingAddress['extension_attributes']['custom_field'] = shippingAddress.customAttributes['custom_field']; // pass execution to original action ('Magento_Checkout/js/action/set-shipping-information') return originalAction();
+            });
+        };
+    }
+);
+```
+
+> When adding a field to the billing address form, you must modify the behavior of 1 of the following components depending on when you need the custom field value to be passed to the server side:
+
+*   `Magento_Checkout/js/action/place-order`
+*   `Magento_Checkout/js/action/set-payment-information`
+
+> To see an example of a mixin that modifies one of these components, see the [place-order-mixin.js](https://github.com/magento/magento2/blob/2.3/app/code/Magento/CheckoutAgreements/view/frontend/web/js/model/place-order-mixin.js&sa=D&ust=1609223265989000&usg=AOvVaw3q57vKPKCuiQYo7xEvHmKy) in the `Magento_CheckoutAgreements` module.
+
+![Magento Section Chevron](./images/icon-chevron.png) Step 3: Load your mixin
+
+> Tell Magento to load your [Mixin](https://magento.stackexchange.com/a/210392/24588&sa=D&ust=1609223265990000&usg=AOvVaw0foDy23DKLB4Rli2SdJeja) for the corresponding [JSComponent](#h.kg229a1fn1nm) by adding the `requirejs-config.js` to the `<module_dir>/view/frontend/` directory.
+>
+> The following code sample shows an example utilizing the sample mixin added earlier:
+
+```js
+var config = {
+    config: {
+        mixins: {
+            'Magento_Checkout/js/action/set-shipping-information': {
+                '<YourNamespace_YourModule>/js/action/set-shipping-information-mixin': true
+            }
+        }
+    }
+};
+```
+
+![Magento Section Chevron](./images/icon-chevron.png) Step 4: Add field to address model
+
+> To add the field to the address model on the server side, add the [extension_attributes.xml](#h.aqe3c923mrz4) file in the `<module_dir>/etc/` directory.
+
+```xml
+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Api/etc/extension_attributes.xsd">
+    <extension_attributes for="Magento\Quote\Api\Data\AddressInterface">
+        <attribute code="custom_field" type="string" />
+    </extension_attributes>
+</config>
+```
+
+> Clear the `generated/code` directory when you run the `setup:di:compile` command. New getter and setter methods will be added in `generated/code/Magento/Quote/Api/Data/AddressExtension.php` file.
+
+![Magento Section Chevron](./images/icon-chevron.png) Step 5: Access the value of the custom field on the server side
+
+> If you completed all the steps described in the previous sections, Magento will generate the interface that includes your custom attribute and you can access your field value.
+>
+> You can set/get these attributes values by creating an instance of the `Magento/Quote/Api/Data/AddressInterface` interface:
+
+```php
+<?php
+
+use Magento\Checkout\Api\Data\ShippingInformationInterface;
+use Magento\Framework\View\Element\Template;
+use Magento\Framework\View\Element\Template\Context;
+
+class MyBlock extends Template
+{
+    /**
+     * @var ShippingInformationInterface
+     */
+    private $_addressInformation;
+
+    /**
+     * @param Context $context
+     * @param ShippingInformationInterface $addressInformation
+     * @param array $data
+     */
+    public function __construct(
+        Context $context,
+        ShippingInformationInterface $addressInformation,
+        array $data = []
+    ) {
+        $this->_addressInformation = $addressInformation;
+        parent::__construct($context, $data);
+    }
+
+    /**
+     * Get custom Shipping Charge
+     *
+     * @return String
+     */
+    public function getShippingCharge()
+    {
+        $extAttributes = $this->_addressInformation->getExtensionAttributes();
+        return $extAttributes->getCustomField(); //get custom attribute data.
+    }
+}
+```
+
+> Finally, compile/deploy code and clean cache with:
+
+```bash
+bin/magento setup:di:compile
+bin/magento setup:static-content:deploy
+bin/magento cache:clean
+```
+
+8.4 Demonstrate ability to customize shipping and payment methods
+-----------------------------------------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**Describe shipping methods architecture. How can you create a new shipping method?**
+
+> Custom Shipping Carriers should implement the following interfaces:
+
+*   `Magento\Shipping\Model\Carrier\CarrierInterface`
+*   `Magento\Shipping\Model\Carrier\AbstractCarrierInterface`
+
+
+> Useful implements
+
+*   `Magento\Shipping\Model\Carrier\AbstractCarrier` - provides a useful class to extend from.
+
+> Notable methods:
+
+*   `getAllowedMethods()` - retrieves all available shipping methods tied to your custom carrier.
+*   `collectRates()` - Calculates the shipping rates (`Magento\Shipping\Model\Rate\ResultFactory`) and method (`Magento\Quote\Model\Quote\Address\RateResult\MethodFactory`) then returns in the form of class: Magento\Shipping\Model\Rate\Result object if the carrier method is available on checkout. Otherwise, it returns false - the carrier method is not applicable to the shopping cart.
+*   `isTrackingAvailable()` - Check if carrier has shipping tracking option available
+
+![Magento Exam Information](./images/icon-info.png)The following is an example for demonstration purposes. Most of the needed information is above.
+
+![Magento Exam Information](./images/icon-info.png)Each shipping carrier can contain one or several shipping rates.
+
+![Magento Exam Information](./images/icon-info.png)Excellent guide here: [https://devdocs.magento.com/guides/v2.4/howdoi/checkout/checkout-add-custom-carrier.html#create-configuration](https://devdocs.magento.com/guides/v2.4/howdoi/checkout/checkout-add-custom-carrier.html%23create-configuration&sa=D&ust=1609223265997000&usg=AOvVaw1fKhrYBResFnSauj3bx2fD)
+
+### Add A Custom Shipping Carrier
+
+![Magento Section Chevron](./images/icon-chevron.png)Add System Configuration
+
+> The [system.xml](#h.op69p944prs) source code declares custom shipping module options.
+>
+> Required parameters for each shipping method:
+
+*   `active` – shipping method enabled / disabled.
+*   `model` – path to shipping method model.
+*   `title` – shipping carrier name; the parameter displays at the front end.
+*   `sallowspecific` – determines whether the shipping method is available for all countries, or for the certain ones.
+*   `sort_order` – the order of shipping methods display in the list.
+
+We also use several additional configuration parameters:
+
+*   `price`;
+*   `name`;
+*   `showmethod` – whether the shipping method is displayed even if it can not be applied to the actual cart / customer.
+
+```xml
+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Config:etc/system_file.xsd">
+    <system>
+        <section id="carriers" translate="label" type="text" sortOrder="320" showInDefault="1" showInWebsite="1" showInStore="1">
+            <group id="customshipping" translate="label" type="text" sortOrder="900" showInDefault="1" showInWebsite="1" showInStore="1">
+                <label>Custom Shipping Module</label>
+                <field id="active" translate="label" type="select" sortOrder="10" showInDefault="1" showInWebsite="1" showInStore="0" canRestore="1">
+                    <label>Enabled</label>
+                    <source_model>Magento\Config\Model\Config\Source\Yesno</source_model>
+                </field>
+                <field id="title" translate="label" type="text" sortOrder="20" showInDefault="1" showInWebsite="1" showInStore="0">
+                    <label>Title</label>
+                </field>
+                <field id="name" translate="label" type="text" sortOrder="30" showInDefault="1" showInWebsite="1" showInStore="0">
+                    <label>Method Name</label>
+                </field>
+                <field id="shipping_cost" translate="label" type="text" sortOrder="40" showInDefault="1" showInWebsite="1" showInStore="0">
+                    <label>Shipping Cost</label>
+                    <validate>validate-number validate-zero-or-greater</validate>
+                </field>
+                <field id="sallowspecific" translate="label" type="select" sortOrder="60" showInDefault="1" showInWebsite="1" showInStore="0" canRestore="1">
+                    <label>Ship to Applicable Countries</label>
+                    <frontend_class>shipping-applicable-country</frontend_class>
+                    <source_model>Magento\Shipping\Model\Config\Source\Allspecificcountries</source_model>
+                </field>
+                <field id="specificcountry" translate="label" type="multiselect" sortOrder="70" showInDefault="1" showInWebsite="1" showInStore="0">
+                    <label>Ship to Specific Countries</label>
+                    <source_model>Magento\Directory\Model\Config\Source\Country</source_model>
+                    <can_be_empty>1</can_be_empty>
+                </field>
+                <field id="showmethod" translate="label" type="select" sortOrder="80" showInDefault="1" showInWebsite="1" showInStore="0">
+                    <label>Show Method if Not Applicable</label>
+                    <source_model>Magento\Config\Model\Config\Source\Yesno</source_model>
+                    <frontend_class>shipping-skip-hide</frontend_class>
+                </field>
+                <field id="sort_order" translate="label" type="text" sortOrder="90" showInDefault="1" showInWebsite="1" showInStore="0">
+                    <label>Sort Order</label>
+                </field>
+            </group>
+        </section>
+    </system>
+</config>
+```
+The [config.xml](#h.glpavwxvxuhd) file specifies default values for custom shipping module options and the shipping module model, MyVendor\MyModule\Model\Carrier\Customshipping:
+
+```xml
+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Store:etc/config.xsd">
+    <default>
+        <carriers>
+            <customshipping>
+                <active>0</active>
+                <title>Custom Shipping Title</title>
+                <name>Custom Shipping Method Name</name>
+                <shipping_cost>10</shipping_cost>
+                <sallowspecific>0</sallowspecific>
+                <sort_order>15</sort_order>
+                <model>MyVendor\MyModule\Model\Carrier\Customshipping</model>
+            </customshipping>
+        </carriers>
+    </default>
+</config>
+```
+
+> In this example, the `MyVendor\MyVendor\Model\Carrier\Customshipping` class is a skeleton of a carrier model. You can extend it to fit your needs.
+>
+> The carrier class implements the `Magento\Shipping\Model\Carrier\CarrierInterface` interface and retrieves all available shipping methods in the `getAllowedMethods` function.
+>
+> The collectRates function returns the `Magento\Shipping\Model\Rate\Result` object if the carrier method is available on checkout. Otherwise, it returns false - the carrier method is not applicable to the shopping cart.
+
+```php
+<?php
+
+namespace MyVendor\MyModule\Model\Carrier;
+
+use Magento\Quote\Model\Quote\Address\RateRequest;
+use Magento\Shipping\Model\Carrier\AbstractCarrier;
+use Magento\Shipping\Model\Carrier\CarrierInterface;
+
+/**
+ * Custom shipping model
+ */
+class Customshipping extends AbstractCarrier implements CarrierInterface
+{
+    /**
+     * @var string
+     */
+    protected $_code = 'customshipping';
+
+    /**
+     * @var bool
+     */
+    protected $_isFixed = true;
+
+    /**
+     * @var \Magento\Shipping\Model\Rate\ResultFactory
+     */
+    private $rateResultFactory;
+
+    /**
+     * @var \Magento\Quote\Model\Quote\Address\RateResult\MethodFactory
+     */
+    private $rateMethodFactory;
+
+    /**
+     * @param Magento\Framework\App\Config\ScopeConfigInterface $scopeConfig
+     * @param \Magento\Quote\Model\Quote\Address\RateResult\ErrorFactory $rateErrorFactory
+     * @param \Psr\Log\LoggerInterface $logger
+     * @param \Magento\Shipping\Model\Rate\ResultFactory $rateResultFactory
+     * @param \Magento\Quote\Model\Quote\Address\RateResult\MethodFactory $rateMethodFactory
+     * @param array $data
+     */
+    public function __construct(
+        Magento\Framework\App\Config\ScopeConfigInterface $scopeConfig,
+        \Magento\Quote\Model\Quote\Address\RateResult\ErrorFactory $rateErrorFactory,
+        \Psr\Log\LoggerInterface $logger,
+        \Magento\Shipping\Model\Rate\ResultFactory $rateResultFactory,
+        \Magento\Quote\Model\Quote\Address\RateResult\MethodFactory $rateMethodFactory,
+        array $data = []
+    ) {
+        parent::__construct($scopeConfig, $rateErrorFactory, $logger, $data);
+        $this->rateResultFactory = $rateResultFactory;
+        $this->rateMethodFactory = $rateMethodFactory;
+    }
+
+    /**
+     * Custom Shipping Rates Collector
+     *
+     * @param RateRequest $request
+     * @return \Magento\Shipping\Model\Rate\Result|bool
+     */
+    public function collectRates(RateRequest $request)
+    {
+        if (!$this->getConfigFlag('active')) {
+            return false;
+        }
+
+        /** @var \Magento\Shipping\Model\Rate\Result $result */
+        $result = $this->rateResultFactory->create();
+
+        /** @var \Magento\Quote\Model\Quote\Address\RateResult\Method $method */
+        $method = $this->rateMethodFactory->create();
+        $method->setCarrier($this->_code);
+        $method->setCarrierTitle($this->getConfigData('title'));
+        $method->setMethod($this->_code);
+        $method->setMethodTitle($this->getConfigData('name'));
+        $shippingCost = (float)$this->getConfigData('shipping_cost');
+        $method->setPrice($shippingCost);
+        $method->setCost($shippingCost);
+        $result->append($method);
+
+        return $result;
+    }
+
+    /**
+     * @return array
+     */
+    public function getAllowedMethods()
+    {
+        return [$this->_code => $this->getConfigData('name')];
+    }
+}
+```
+
+> This shipping method model should inherit `Magento\Shipping\Model\Carrier\AbstractCarrier` class and realize the interface: `Magento\Shipping\Model\Carrier\CarrierInterface`; it also should have at least two methods:
+
+*   `getAllowedMethods()` - Should return the options array, available for our method (standard or fast delivery
+*   `collectRates()` - When returned, false deletes the given shipping method from the list of available ones. An instance of `Magento\Shipping\Model\Rate\Result` with the list of available methods.
+
+> `$_code` parameters in this model should contain a unique shipping method code; in our case, it's "`customshipping`".
+>
+> `$this->getConfigData` method allows us to get the configuration values for our method (based on the available in `system.xml` file).
+
+![Magento Exam Question](./images/icon-question.png)**What is the relationship between carriers and rates?**
+
+> The Shipping Carrier is responsible for calculating the shipping rate. In the example above the collectRates method returns the `Magento\Shipping\Model\Rate\Result` object if the carrier method is available on checkout. Otherwise, it returns false - the carrier method is not applicable to the shopping cart.
+
+![Magento Exam Question](./images/icon-question.png)**Describe how to troubleshoot shipping methods and rate results. Where do shipping rates come from? How can you debug the wrong shipping rate being returned?**
+
+> Debugging (specifically) any implementation of `Magento\Shipping\Model\Carrier\AbstractCarrierInterface::collectRates` method - This can be applied to check the availability of the given method for a certain customer. For instance, if we need to limit the method availability to certain postcodes only, this check should be performed there.
+>
+> Debugging (more generically) `Magento\Shipping\Model\Shipping::collectCarrierRates` - This method can also be used to set up shipping methods.
+
+![Magento Exam Question](./images/icon-question.png)**How would you create a custom payment method?**
+
+### Creating a Custom Payment Method
+
+![Magento Section Chevron](./images/icon-chevron.png) Magento Payment Provider Gateway
+
+> Via the Magento Payment Provider Gateway.
+> The [Magento Payment Provider Gateway](https://devdocs.magento.com/guides/v2.4/payments-integrations/payment-gateway/payment-gateway-intro.html&sa=D&ust=1609223266031000&usg=AOvVaw2JMnBII16zg8WgMm-u2fsD) is a mechanism that allows you to integrate your stores with payment service providers. As a result, you can create and handle transactions based on order details.
+>
+>
+> The following diagram shows a simplified interaction flow between Magento sales management and external payment service provider using Magento payment provider gateway:
+
+![](./images/Magento2-Certification-Exam-Notes-Detailed-Insight-Custom-Payment-Method.png)
+
+> Magento Payment Provider Gateway supports the following payment operations:
+
+*   `authorize`: process authorization transaction; funds are blocked on customer account, but not withdrawn.
+*   `sale`: process authorization transaction and capture automatically, funds are withdrawn
+*   `capture`: withdraw previously authorized amount
+*   `refund`: return previously withdrawn customer funds
+*   `void`: cancel transfer of funds from customer account
+
+Magento/Adobe Commmerce Docs:
+*   [Gateway Command](https://devdocs.magento.com/guides/v2.4/payments-integrations/payment-gateway/gateway-command.html&sa=D&ust=1609223266034000&usg=AOvVaw0xW8bx38jNelik8V6A6ldI)
+*   [Gateway Command Pool](https://devdocs.magento.com/guides/v2.4/payments-integrations/payment-gateway/command-pool.html&sa=D&ust=1609223266035000&usg=AOvVaw2cebpKrBnX07gjsQIjoKbI)
+*   [Request Builder](https://devdocs.magento.com/guides/v2.4/payments-integrations/payment-gateway/request-builder.html&sa=D&ust=1609223266036000&usg=AOvVaw2pBlDomdZEHLTPgopOGOoi)
+*   [Gateway Client](https://devdocs.magento.com/guides/v2.4/payments-integrations/payment-gateway/gateway-client.html&sa=D&ust=1609223266036000&usg=AOvVaw265YoxwWOV_iUSNZAgMpq9)
+*   [Response Validator](https://devdocs.magento.com/guides/v2.4/payments-integrations/payment-gateway/response-validator.html&sa=D&ust=1609223266037000&usg=AOvVaw32-HL99ZScRsTKna-yhGBL)
+*   [Response Handler](https://devdocs.magento.com/guides/v2.4/payments-integrations/payment-gateway/response-handler.html&sa=D&ust=1609223266037000&usg=AOvVaw2wkAnID_bynK9Y-03Im3lI)
+
+![Magento Exam Information](./images/icon-info.png)If nothing else, remember this information. The rest is further detail.
+
+![Magento Section Chevron](./images/icon-chevron.png)Declare Payment Method
+
+> Declare a new Payment method via declarative schema, make it visible via:
+>
+> Admin panel > Stores > Settings > Configuration > Sales > Payment Methods
+
+`payment.xml`
+```xml
+<?xml version="1.0" ?>
+<payment xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Payment:etc/payment.xsd">
+    <groups>
+        <group id="offline">
+            <label>Example Payment Methods</label>
+        </group>
+    </groups>
+    <methods>
+        <method name="example">
+            <allow_multiple_address>1</allow_multiple_address>
+        </method>
+    </methods>
+</payment>
+```
+
+`config.xml`
+```xml
+<?xml version="1.0" ?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Store:etc/config.xsd">
+    <default>
+        <payment>
+            <example>
+                <active>1</active>
+                <model>Mageplaza\Payment\Model\Payment\Simple</model>
+                <order_status>pending</order_status>
+                <title>Example - Test</title>
+                <allowspecific>0</allowspecific>
+                <group>Offline</group>
+            </example>
+        </payment>
+    </default>
+</config>
+```
+
+![Magento Section Chevron](./images/icon-chevron.png) Gateway Command Pool
+
+> All Gateway Commands implemented for a particular payment provider, should be added to a command pool for this provider. A Gateway Command Pool is a set of gateway commands available for integration with a particular payment provider. The pool is added to the configuration of the payment provider using [Dependency Injection](#h.9ofwnl5q9fnf). Pools are Virtual Types that extend Magento\Payment\Gateway\Command\CommandPool which implements Magento\Payment\Gateway\Command\CommandPoolInterface
+>
+> Below is an example of a Gateway Command Pool
+
+```xml
+...
+
+<!-- ExampleCommandPool - a command pool for the Example payments provider -->
+<virtualType name="ExampleCommandPool" type="Magento\Payment\Gateway\Command\CommandPool">
+    <arguments>
+        <argument name="commands" xsi:type="array">
+            <item name="authorize" xsi:type="string">ExampleAuthorizeCommand</item>
+            <item name="sale" xsi:type="string">ExampleSaleCommand</item>
+            <item name="capture" xsi:type="string">ExampleCaptureStrategyCommand</item>
+        </argument>
+    </arguments>
+</virtualType>
+
+...
+
+<!-- Adding ExampleCommandPool to the Example payment method configuration:-->
+<virtualType name="ExampleFacade" type="Magento\Payment\Model\Method\Adapter">
+    <arguments>
+        <argument name="commandPool" xsi:type="object">ExampleCommandPool</argument>
+    </arguments>
+</virtualType>
+
+...
+```
+
+![Magento Section Chevron](./images/icon-chevron.png) Gateway Command
+
+> A Gateway Command is a component of the Magento Payment Gateway
+>
+> It takes the payload required for a particular payment provider which sends, receives, and processes the provider's response. For each operation (authorization, capture and so on) of a certain payment provider - a separate gateway command is specified.
+>
+> In the example above you can see that the authorize, sale and capture commands are specified in the Gateway Command Pool
+>
+> Below is an example of the authorize command specified as a Virtual Type in [Dependency Injection](#h.9ofwnl5q9fnf):
+
+```xml
+<virtualType name="ExampleAuthorizeCommand" type="Magento\Payment\Gateway\Command\GatewayCommand">
+    <arguments>
+        <argument name="requestBuilder" xsi:type="object">ExampleAuthorizeRequest</argument>
+        <argument name="transferFactory" xsi:type="object">MyVendor\MyModule\Gateway\Http\TransferFactory</argument>
+        <argument name="client" xsi:type="object">MyVendor\MyModule\Gateway\Http\Client\TransactionSale</argument>
+        <argument name="handler" xsi:type="object">ExampleAuthorizationHandler</argument>
+        <argument name="validator" xsi:type="object">MyVendor\MyModule\Gateway\Validator\ResponseValidator</argument>
+        <argument name="errorMessageMapper" xsi:type="object">MyVendor\MyModule\Gateway\ErrorMapper\VirtualErrorMessageMapper</argument>
+    </arguments>
+</virtualType>
+```
+
+> A Gateway Command must be configured with the following arguments:
+
+*   `requestBuilder`: request builder, builds an array of provider-specific arguments using the order information. More info in the subsection below.
+*   `transferFactory`: transfer factory, creates transfer object from request data, which will be used by Gateway Client to process requests. More info in the subsection below. For more details see [Gateway Client #Transfer Factory](https://devdocs.magento.com/guides/v2.4/payments-integrations/payment-gateway/gateway-client.html%23transfer_factory&sa=D&ust=1609223266049000&usg=AOvVaw1tzwYvLXxg6VNRKgfJQgq2)
+*   `client`: gateway client, takes the provider-specific arguments and performs a low-level call to the provider. More info in the subsection below.
+*   Optional arguments:
+
+    *   `handler`: response handler, changes the order and payment status depending on the payment provider response. More info in the subsection below.
+    *   `validator`: response validator, validates the provider response. More info in the subsection below.
+
+![Magento Section Chevron](./images/icon-chevron.png) Request Builder
+
+> Request Builder is a component of the Magento Payment Gateway
+>
+> It's responsible for building a request from several parts. It allows implementing complex, yet atomic and testable, building strategies.
+>
+> Each builder can have simple logic or can contain builder composites.
+>
+> The Request Builder may be configured as the requestBuilder argument of the Gateway Command using [Dependency Injection](#h.9ofwnl5q9fnf) (above).
+>
+> Builder compositeWhen creating Builder Composites: each instance extends the `Magento\Payment\Gateway\Request\BuilderComposite` class and is a container for a list of \Magento\Payment\Gateway\Request\BuilderInterface implementations. It gets a list of classes, or types, or virtual type names, and performs a lazy instantiation on an actual BuilderComposite::build([]) call. So that you can have as many objects as required, but only those, which are needed for a request are instantiated.
+>
+> `BuilderComposite` implements the composite design pattern.Adding A Builder CompositeBuilder composites are added using [Dependency Injection](#h.9ofwnl5q9fnf) in di.xml. A builder composite might comprise simple builders as well as other builder composites.
+>
+> Example of adding composite builders for the Braintree payment provider (`app/code/Magento/Braintree/etc/di.xml`):
+
+```xml
+...
+
+<!--  is a builder composite comprising a number of builders -->
+<virtualType name="BraintreeAuthorizeRequest" type="Magento\Payment\Gateway\Request\BuilderComposite">
+    <arguments>
+        <argument name="builders" xsi:type="array">
+            <item name="customer" xsi:type="string">Magento\Braintree\Gateway\Request\CustomerDataBuilder</item>
+            <item name="payment" xsi:type="string">Magento\Braintree\Gateway\Request\PaymentDataBuilder</item>
+            <item name="channel" xsi:type="string">Magento\Braintree\Gateway\Request\ChannelDataBuilder</item>
+            <item name="address" xsi:type="string">Magento\Braintree\Gateway\Request\AddressDataBuilder</item>
+            <item name="vault" xsi:type="string">Magento\Braintree\Gateway\Request\VaultDataBuilder</item>
+            <item name="3dsecure" xsi:type="string">Magento\Braintree\Gateway\Request\ThreeDSecureDataBuilder</item>
+            <item name="device_data" xsi:type="string">Magento\Braintree\Gateway\Request\KountPaymentDataBuilder</item>
+            <item name="dynamic_descriptor" xsi:type="string">Magento\Braintree\Gateway\Request\DescriptorDataBuilder</item>
+            <item name="store" xsi:type="string">Magento\Braintree\Gateway\Request\StoreConfigBuilder</item>
+            <item name="merchant_account" xsi:type="string">Magento\Braintree\Gateway\Request\MerchantAccountDataBuilder</item>
+        </argument>
+    </arguments>
+</virtualType>
+
+...
+
+<!-- The same BraintreeAuthorizeRequest builder composite is a part of the BraintreeSaleRequest builder composite -->
+<virtualType name="BraintreeSaleRequest" type="Magento\Payment\Gateway\Request\BuilderComposite">
+    <arguments>
+        <argument name="builders" xsi:type="array">
+            <item name="authorize" xsi:type="string">BraintreeAuthorizeRequest</item>
+            <item name="settlement" xsi:type="string">Magento\Braintree\Gateway\Request\SettlementDataBuilder</item>
+        </argument>
+    </arguments>
+</virtualType>
+```
+
+![Magento Section Chevron](./images/icon-chevron.png) Gateway Client
+
+> Gateway Client is a component of the Magento Payment Gateway
+>
+> It transfers the payload to the payment provider and gets the response and must implement `Magento\Payment\Gateway\Http\ClientInterface`.
+>
+> A gateway client receives a called Transfer Object.
+>
+> The client may be configured as the client argument of the Gateway Command with a response converter using [Dependency Injection](#h.9ofwnl5q9fnf).
+>
+> An example of a concrete implementation of `Magento\Payment\Gateway\Http\ClientInterface` might look like the following. Here transfer factory sets all required data to process requests using API credentials and all data is sent in JSON format:
+
+```php
+<?php
+
+......
+
+public function create(array $request)
+{
+    return $this->transferBuilder
+        ->setMethod(Curl::POST)
+        ->setHeaders(['Content-Type' => 'application/json'])
+        ->setBody(json_encode($request, JSON_UNESCAPED_SLASHES))
+        ->setAuthUsername($this->getApiKey())
+        ->setAuthPassword($this->getApiPassword())
+        ->setUri($this->getUrl())
+        ->build();
+}
+
+```
+![Magento Section Chevron](./images/icon-chevron.png) Response Validator
+
+> The Response Validator is a component of the Magento Payment Provider Gateway
+>
+> It performs gateway response verification. This may include:
+
+*   Low level data formatting
+*   Security verification,
+*   And even execution of some business logic required by the store configuration.
+
+> Response Validator returns an object that implements interface: `Magento\Payment\Gateway\Validator\ResultInterface`, containing validation result as Boolean value and errors description as a list of Magento "Phrases" (localised string).
+>
+> Response Validator must implement Magento\Payment\Gateway\Validator\ValidatorInterface
+>
+> Useful Implementations:
+
+*   `Magento\Payment\Gateway\Validator\AbstractValidator` - an abstract class with ability to create a Result object. Can be inherited from by particular response validator implementations.
+*   `Magento\Payment\Gateway\Validator\ValidatorComposite` - a chain of Validator objects, which are executed one by one and the result gets aggregated into one Result object. This chain can be configured to stop when certain validators fail.
+*   `Magento\Payment\Gateway\Validator\Result` - a base class for Result object. You still have an ability to create a Result of your own, but the default one covers the most amount of cases.
+
+> In the following example a Response Validator is implemented and added to the pool of the Braintree payment provider request validators:
+
+```php
+<?php
+
+class AcceptValidator extends AbstractValidator
+{
+    /**
+     * Performs domain-related validation for business object
+     *
+     * @param array $validationSubject
+     * @return ResultInterface
+     */
+    public function validate(array $validationSubject)
+    {
+        $response = SubjectReader::readResponse($validationSubject);
+        $paymentDO = SubjectReader::readPayment($validationSubject);
+        $isValid = true;
+        $fails = [];
+        $statements = [
+            [
+                $paymentDO->getOrder()->getCurrencyCode() === $response['authCurrency'],
+                __('Currency doesn\'t match.')
+            ],
+            [
+                sprintf(
+                    '%.2F',
+                    $paymentDO->getOrder()->getGrandTotalAmount()
+                ) === $response['authCost'],
+                __('Amount doesn\'t match.')
+            ],
+            [
+                in_array($response['authMode'], ['A', 'E']),
+                __('Not supported response.')
+            ]
+        ];
+
+        foreach ($statements as $statementResult) {
+            if (!$statementResult[0]) {
+                $isValid = false;
+                $fails[] = $statementResult[1];
+            }
+        }
+
+        return $this->createResult($isValid, $fails);
+    }
+}
+```
+
+![Magento Section Chevron](./images/icon-chevron.png) Response Handler
+
+> Response Handler is the component of Magento Payment Provider Gateway
+>
+> It processes payment provider response, typically the response requires one of the following actions:
+
+*   Modify the order status
+*   Save information that was provided in a transaction response
+*   Send an email
+
+> A custom Response Handler must implement interface: `Magento\Payment\Gateway\Response\HandlerInterface`
+>
+> Useful implementations
+
+*   `Magento\Payment\Gateway\Response\HandlerChain` might be used as a basic container of response handlers, handling different parts.
+
+> In the following example a Response Handler is implemented and added to the pool of the Braintree payment provider:
+
+```php
+<?php
+
+class PayPalDetailsHandler implements HandlerInterface
+{
+    const PAYMENT_ID = 'paymentId';
+    const PAYER_EMAIL = 'payerEmail';
+
+    /**
+     * @var SubjectReader
+     */
+    private $subjectReader;
+
+    /**
+     * Constructor
+     *
+     * @param SubjectReader $subjectReader
+     */
+
+    public function __construct(SubjectReader $subjectReader)
+    {
+        $this->subjectReader = $subjectReader;
+    }
+
+    /**
+     * @inheritdoc
+     */
+    public function handle(array $handlingSubject, array $response)
+    {
+        $paymentDO = $this->subjectReader->readPayment($handlingSubject);
+
+        /** @var \Braintree\Transaction $transaction */
+        $transaction = $this->subjectReader->readTransaction($response);
+
+        /** @var OrderPaymentInterface $payment */
+        $payment = $paymentDO->getPayment();
+        $payPal = $this->subjectReader->readPayPal($transaction);
+        $payment->setAdditionalInformation(self::PAYMENT_ID, $payPal[self::PAYMENT_ID]);
+        $payment->setAdditionalInformation(self::PAYER_EMAIL, $payPal[self::PAYER_EMAIL]);
+    }
+}
+
+```
+
+![Magento Exam Information](./images/icon-info.png)The Response Handler only modifies the order state, based on the payment gateway response. It does not perform any other required actions.
+
+![Magento Section Chevron](./images/icon-chevron.png) Display Payment Method
+
+> [https://devdocs.magento.com/guides/v2.4/howdoi/checkout/checkout_payment.html](https://devdocs.magento.com/guides/v2.4/howdoi/checkout/checkout_payment.html&sa=D&ust=1609223266068000&usg=AOvVaw3xziC83RvKQxkjDnn1uiG3)
+
+![Magento Exam Question](./images/icon-question.png)**Describe how to troubleshoot payment methods. What types of payment methods exist?**
+
+> In Magento 2, there are three payment method types:
+
+
+1.  [Gateway](#h.ctho0c6bcdkk) - payment data is passed first into Magento, and then - to the merchant. To enhance safety, use payment data tokenization.
+2.  Offline - the payment method that does not provide for the connection with any third-party payment provider. Examples: Check/Money Order, Bank Transfer, Purchase Order and Cash on Delivery.
+3.  Hosted - redirects the customer to the payment page that is not a part of Magento 2.
+
+
+> Each Gateway Payment Provider is divided into a different number of Request Builder commands:
+
+*   `fetch_transaction_information`
+*   `order`
+*   `authorize`
+*   `capture`
+*   `refund`
+*   `cancel`
+*   `void`
+*   `acceptPayment`
+*   `denyPayment`
+
+
+> Each command should be realized as a separate class; therefore, payment methods debugging should begin with the class of the corresponding command.
+
+![Magento Exam Question](./images/icon-question.png)**What are the different payment flows?**
+
+> Offline and online. While both utilize the same implementation, offline payment methods usually do very little with the authorize and capture steps. On the other hand, online payments utilize these steps to communicate with the external API to ensure funds are available, capture them, and refund the funds.
\ No newline at end of file
diff --git a/9. Sales Operations/9.1 Demonstrate ability to customize sales operations.md b/9. Sales Operations/9.1 Demonstrate ability to customize sales operations.md
deleted file mode 100644
index d68fac1..0000000
--- a/9. Sales Operations/9.1 Demonstrate ability to customize sales operations.md	
+++ /dev/null
@@ -1,15 +0,0 @@
-## 9.1 Demonstrate ability to customize sales operations
-
-Describe how to modify order processing and integrate it with a third-party ERP system.
-
-*Describe how to modify order processing flow. How would you add new states and statuses for an order?*
-
-*How do you change the behavior of existing states and statuses?*
-
-Described how to customize invoices. 
-
-*How would you customize invoice generation, capturing, and management?*
-
-Describe refund functionality in Magento. 
-
-*Which refund types are available, and how are they used?*
diff --git a/9.Magento-Sales-Operations.md b/9.Magento-Sales-Operations.md
new file mode 100755
index 0000000..38770e6
--- /dev/null
+++ b/9.Magento-Sales-Operations.md
@@ -0,0 +1,945 @@
+9 - Sales Operations
+====================
+
+9.1 Demonstrate ability to customize sales operations
+-----------------------------------------------------
+
+![Magento Exam Question](./images/icon-question.png)**Describe the Order entity**
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Sales Order
+
+> Like all Modules, Magento_Sales uses the [Service Contracts](#h.i0qq8aqgijv7) design pattern to manage (C.R.U.D actions) Sales Orders with the following Repositories:
+>
+> Order repository interface.
+>
+> The main interface for managing (C.R.U.D actions) Sales Orders.
+>
+> An order is a document that a web store issues to a customer. Magento generates a sales order that lists the product items, billing and shipping addresses, and shipping and payment methods. A corresponding external document, known as a purchase order, is emailed to the customer.
+
+```php
+Magento\Sales\Api\OrderRepositoryInterface::save(
+        Magento\Sales\Api\Data\OrderInterface $entity
+);
+```
+
+> Credit memo repository interface.
+>
+> After a customer places and pays for an order and an invoice has been issued, the merchant can create a credit memo to refund all or part of the amount paid for any returned or undelivered items. The memo restores funds to the customer account so that the customer can make future purchases.
+
+```php
+Magento\Sales\Api\CreditmemoRepositoryInterface::save(
+        Magento\Sales\Api\Data\CreditmemoInterface $entity
+);
+```
+
+> Credit memo management interface.
+>
+> After a customer places and pays for an order and an invoice has been issued, the merchant can create a credit memo to refund all or part of the amount paid for any returned or undelivered items. The memo restores funds to the customer account so that the customer can make future purchases.
+
+```php
+Magento\Sales\Api\CreditmemoManagementInterface::refund(
+        Magento\Sales\Api\Data\CreditmemoInterface $creditmemo
+);
+```
+
+> Credit memo item repository interface.
+>
+> After a customer places and pays for an order and an invoice has been issued, the merchant can create a credit memo to refund all or part of the amount paid for any returned or undelivered items. The memo restores funds to the customer account so that the customer can make future purchases. A credit memo item is an invoiced item for which a merchant creates a credit memo.
+
+```php
+Magento\Sales\Api\CreditmemoItemRepositoryInterface::save(
+        Magento\Sales\Api\Data\CreditmemoItemInterface $entity
+);
+```
+
+> Credit memo comment repository interface.
+>
+> After a customer places and pays for an order and an invoice has been issued, the merchant can create a credit memo to refund all or part of the amount paid for any returned or undelivered items. The memo restores funds to the customer account so that the customer can make future purchases. A credit memo usually includes comments that detail why the credit memo amount was credited to the customer:
+
+```php
+Magento\Sales\Api\CreditmemoCommentRepositoryInterface::get(
+        int $id
+);
+```
+
+> Invoice repository interface.
+>
+> An invoice is a record of the receipt of payment for an order.
+
+```php
+Magento\Sales\Api\InvoiceRepositoryInterface::save(
+        \Magento\Sales\Api\Data\InvoiceInterface $entity
+);
+```
+
+> Invoice management interface.
+>
+> An invoice is a record of the receipt of payment for an order.
+
+```php
+Magento\Sales\Api\InvoiceManagementInterface::notify(
+        int $id
+);
+```
+
+> Invoice Order Interface
+>
+> The interface for invoicing orders setting them as paid.
+
+```php
+Magento\Sales\Api\InvoiceOrderInterface::execute(
+        int $orderId,
+        bool $capture = false,
+        Magento\Sales\Api\Data\InvoiceItemCreationInterface[] $items = [],
+        bool $notify = false,
+        bool $appendComment = false,
+        Magento\Sales\Api\Data\InvoiceCommentCreationInterface $comment = null,
+        Magento\Sales\Api\Data\InvoiceCreationArgumentsInterface $arguments = null
+);
+```
+
+> Invoice item repository interface.
+>
+> An invoice is a record of the receipt of payment for an order. An invoice item is a purchased item in an invoice.
+
+```php
+Magento\Sales\Api\InvoiceItemRepositoryInterface::save(
+        \Magento\Sales\Api\Data\InvoiceItemInterface $entity
+);
+```
+
+> Invoice comment repository interface.
+>
+> An invoice is a record of the receipt of payment for an order. An invoice can include comments that detail the invoice history.
+
+```php
+Magento\Sales\Api\InvoiceCommentRepositoryInterface::save(
+        \Magento\Sales\Api\Data\InvoiceCommentInterface $entity
+);
+```
+
+> Order address repository interface.
+>
+> An order is a document that a web store issues to a customer. Magento generates a sales order that lists the product items, billing and shipping addresses, and shipping and payment methods. A corresponding external document, known as a purchase order, is emailed to the customer.
+
+```php
+Magento\Sales\Api\OrderAddressRepositoryInterface::save(
+        Magento\Sales\Api\Data\OrderAddressInterface $entity
+);
+```
+
+> Order item repository interface.
+>
+> The main interface for CRUD actions on Order Items.
+>
+> An order is a document that a web store issues to a customer. Magento generates a sales order that lists the product items, billing and shipping addresses, and shipping and payment methods. A corresponding external document, known as a purchase order, is emailed to the customer.
+
+```php
+Magento\Sales\Api\OrderItemRepositoryInterface::save(
+        Magento\Sales\Api\Data\OrderItemInterface $entity
+);
+```
+
+> Order management interface.
+>
+> An order is a document that a web store issues to a customer. Magento generates a sales order that lists the product items, billing and shipping addresses, and shipping and payment methods. A corresponding external document, known as a purchase order, is emailed to the customer.
+
+```php
+Magento\Sales\Api\OrderManagementInterface::place(
+        Magento\Sales\Api\Data\OrderInterface $order
+);
+```
+
+> Order payment repository interface.
+>
+> The main interface for C.R.U.D actions on Order Payment entities.
+>
+> An order is a document that a web store issues to a customer. Magento generates a sales order that lists the product items, billing and shipping addresses, and shipping and payment methods. A corresponding external document, known as a purchase order, is emailed to the customer.
+
+```php
+Magento\Sales\Api\OrderPaymentRepositoryInterface::save(
+        Magento\Sales\Api\Data\OrderPaymentInterface $entity
+);
+```
+
+> Order status history repository interface.
+>
+> An order is a document that a web store issues to a customer. Magento generates a sales order that lists the product items, billing and shipping addresses, and shipping and payment methods. A corresponding external document, known as a purchase order, is emailed to the customer.
+
+```php
+Magento\Sales\Api\OrderStatusHistoryRepositoryInterface::save(
+        Magento\Sales\Api\Data\OrderStatusHistoryInterface $entity
+);
+```
+
+> Order Customer Management Interface
+>
+> Create a [Customer Entity](#h.u2g6b8nkpo4) account from an order ID.
+
+```php
+Magento\Sales\Api\OrderCustomerManagementInterface::create(
+        int $orderId
+);
+```
+
+> Refund Invoice Interface
+>
+> Create refund for invoice
+
+```php
+Magento\Sales\Api\RefundInvoiceInterface::execute(
+        $invoiceId,
+        array $items = [],
+        $isOnline = false,
+        $notify = false,
+        $appendComment = false,
+        \Magento\Sales\Api\Data\CreditmemoCommentCreationInterface $comment = null,
+        \Magento\Sales\Api\Data\CreditmemoCreationArgumentsInterface $arguments = null
+);
+```
+
+> Refund Order Interface
+>
+> Create offline refund for order
+
+```php
+Magento\Sales\Api\RefundOrderInterface::execute(
+        $orderId,
+        array $items = [],
+        $notify = false,
+        $appendComment = false,
+        \Magento\Sales\Api\Data\CreditmemoCommentCreationInterface $comment = null,
+        \Magento\Sales\Api\Data\CreditmemoCreationArgumentsInterface $arguments = null
+);
+```
+
+> Payment Failures Interface
+>
+> Interface for managing payment gateway failures.
+
+```php
+Magento\Sales\Api\PaymentFailuresInterface::handle(
+        int $cartId,
+        string $errorMessage,
+        string $checkoutType = 'onepage'
+): PaymentFailuresInterface;
+```
+
+> Delegate related to orders customers operations to Customer module.
+>
+> Redirect to Customer module new-account page to finish creating customer based on order data.
+
+```php
+Magento\Sales\Api\OrderCustomerDelegateInterface::delegateNew(
+        int $orderId
+): Redirect;
+```
+
+> Shipment item repository interface.
+>
+> A shipment is a delivery package that contains products. A shipment document accompanies the shipment. This document lists the products and their quantities in the delivery package. A product is an item in a shipment.
+
+```php
+Magento\Sales\Api\ShipmentItemRepositoryInterface::save(
+        \Magento\Sales\Api\Data\ShipmentItemInterface $entity
+);
+```
+
+> Shipment management interface.
+>
+> A shipment is a delivery package that contains products. A shipment document accompanies the shipment. This document lists the products and their quantities in the delivery package.
+
+```php
+Magento\Sales\Api\ShipmentManagementInterface::notify(
+        int $id
+);
+```
+
+> Shipment repository interface.
+>
+> The main interface for C.R.U.D actions on Order Shipment Entities
+>
+> A shipment is a delivery package that contains products. A shipment document accompanies the shipment. This document lists the products and their quantities in the delivery package.
+
+```php
+Magento\Sales\Api\ShipmentRepositoryInterface::save(
+        \Magento\Sales\Api\Data\ShipmentInterface $entity
+);
+```
+
+> Shipment track repository interface.
+>
+> A shipment is a delivery package that contains products. A shipment document accompanies the shipment. This document lists the products and their quantities in the delivery package.
+
+```php
+Magento\Sales\Api\ShipmentTrackRepositoryInterface::save(
+        \Magento\Sales\Api\Data\ShipmentTrackInterface $entity
+);
+```
+
+> Ship Order Interface
+>
+> Creates new Shipment for given Order.
+
+```php
+Magento\Sales\Api\ShipOrderInterface::execute(
+        $orderId,
+        array $items = [],
+        $notify = false,
+        $appendComment = false,
+        \Magento\Sales\Api\Data\ShipmentCommentCreationInterface $comment = null,
+        array $tracks = [],
+        array $packages = [],
+        \Magento\Sales\Api\Data\ShipmentCreationArgumentsInterface $arguments = null
+);
+```
+
+> Shipment comment repository interface.
+>
+> A shipment is a delivery package that contains products. A shipment document accompanies the shipment. This document lists the products and their quantities in the delivery package. A shipment document can contain comments.
+
+```php
+Magento\Sales\Api\ShipmentCommentRepositoryInterface::save(
+        \Magento\Sales\Api\Data\ShipmentCommentInterface $entity
+);
+```
+
+> Transaction repository interface.
+>
+> The main interface for CRUD actions on a Transaction entity.
+>
+> A transaction is an interaction between a merchant and a customer such as a purchase, a credit, a refund, and so on.
+
+```php
+Magento\Sales\Api\TransactionRepositoryInterface::save(
+        \Magento\Sales\Api\Data\TransactionInterface $entity
+);
+```
+
+![Magento Exam Information](./images/icon-info.png)Main thing to take away here is that The `Sales_Order` module is responsible for the Sales Order Entity. In this module contains Repositories that follow the [Service Contract](https://devdocs.magento.com/guides/v2.3/extension-dev-guide/service-contracts/service-contracts.html&sa=D&ust=1609223266106000&usg=AOvVaw3X_KS_UuGtifIdTL1l1NI6) design pattern to deliver injectable C.R.U.D actions on Sales Orders, Credit Memos, Comments, Sales Order Items, Invoices, Sales Addresses, Payments, Transactions & Shipment entities.
+
+| Database Table: **`sales_order`** | Notable  Columns | Description |
+| --- | --- | --- |
+| Core Sales Order properties | `entity_id` - int(10), `increment_id` - varchar(32), state - varchar(32), status - varchar(32), `is_virtual` - smallint(5), `store_id` - smallint(5), `protect_code` - varchar(255), `base_discount_amount` - decimal(20,4), `base_discount_canceled` - decimal(20,4), `base_discount_invoiced` - decimal(20,4), `base_discount_refunded` - decimal(20,4), `base_grand_total` - decimal(20,4), `base_subtotal` - decimal(20,4), `base_subtotal_canceled` - decimal(20,4), `base_subtotal_invoiced` - decimal(20,4), `base_subtotal_refunded` - decimal(20,4), `base_tax_amount` - decimal(20,4), `base_tax_canceled` - decimal(20,4), `base_tax_invoiced` - decimal(20,4), `base_tax_refunded` - decimal(20,4), `base_to_global_rate` - decimal(20,4), `base_to_order_rate` - decimal(20,4), `base_total_canceled` - decimal(20,4), `base_total_invoiced` - decimal(20,4), `base_total_invoiced_cost` - decimal(20,4), `base_total_offline_refunded` - decimal(20,4), `base_total_online_refunded` - decimal(20,4), `base_total_paid` - decimal(20,4), `base_total_qty_ordered` - decimal(12,4), `base_total_refunded` - decimal(20,4), `discount_amount` - decimal(20,4), `discount_canceled` - decimal(20,4), `discount_invoiced` - decimal(20,4), `discount_refunded` - decimal(20,4), `grand_total` - decimal(20,4), `store_to_base_rate` - decimal(12,4), `store_to_order_rate` - decimal(12,4), subtotal - decimal(20,4), `subtotal_canceled` - decimal(20,4), `subtotal_invoiced` - decimal(20,4), `subtotal_refunded` - decimal(20,4), `total_canceled` - decimal(20,4), `total_invoiced` - decimal(20,4), `total_offline_refunded` - decimal(20,4), `total_online_refunded` - decimal(20,4), `total_paid` - decimal(20,4), `total_qty_ordered` - decimal(12,4), `total_refunded` - decimal(20,4), `edit_increment` - int(11), `email_sent` - smallint(5), `send_email` - smallint(5), `forced_shipment_with_invoice` - smallint(5), `payment_auth_expiration` - int(11), `quote_address_id` - int(11), `quote_id` - int(11), `adjustment_negative` - decimal(20,4), `adjustment_positive` - decimal(20,4), `base_adjustment_negative` - decimal(20,4), `base_adjustment_positive` - decimal(20,4), `base_subtotal_incl_tax` - decimal(20,4), `base_total_due` - decimal(20,4), `payment_authorization_amount` - decimal(20,4), `subtotal_incl_tax` - decimal(20,4), `total_due` - decimal(20,4), weight - decimal(12,4), `base_currency_code` - varchar(3), `discount_description` - varchar(255), `ext_order_id` - varchar(32), `global_currency_code` - varchar(3), `hold_before_state` - varchar(32), `hold_before_status` - varchar(32), `order_currency_code` - varchar(3), `original_increment_id` - varchar(32), `relation_child_id` - varchar(32), `relation_child_real_id` - varchar(32), `relation_parent_id` - varchar(32), `relation_parent_real_id` - varchar(32), `remote_ip` - varchar(45), `store_currency_code` - varchar(3), `store_name` - varchar(32), `x_forwarded_for` - varchar(32), `customer_note` - text, `created_at` - timestamp, `updated_at` - timestamp, `total_item_count` - smallint(5), `tax_amount` - decimal(20,4), `tax_canceled` - decimal(20,4), `tax_invoiced` - decimal(20,4), `tax_refunded` - decimal(20,4), `discount_tax_compensation_amount` - decimal(20,4), `base_discount_tax_compensation_amount` - decimal(20,4), `discount_tax_compensation_invoiced` - decimal(20,4), `base_discount_tax_compensation_invoiced` - decimal(20,4), `discount_tax_compensation_refunded` - decimal(20,4), `base_discount_tax_compensation_refunded`, `paypal_ipn_customer_notified` - int(11) | `entity_id`: used all over the code and is the global identifier. `increment_id`:  Unique identifier for an order, and commonly referred to as the `order_id` within Magento. The `increment_id` is most often used for joins to external sources, such as Google Ecommerce. `status`: Order's status. May return values such as ‘complete', ‘processing', ‘cancelled', ‘refunded', as well as any custom statuses implemented on the Magento instance. Subject to changes as the order gets processed. `store_id`: Foreign key associated with the store table. Join to store.`store_id` to determine which Magento store view is associated with the order. `is_virtual`: Relating to [Virtual Products](#h.t3fkw0wf3trp) / [Downloadable Products](#h.614rvm49j6y9). `grand_total`: The final price of the Quote/Cart. `subtotal`: Total of all Cart Items prices * by the Cart Item Qtys, before tax or discount. `base_currency_code`:  Currency for all values captured in `base_*` fields (that is `base_grand_total`, `base_subtotal`, and so on). This typically reflects the Magento store's default currency. `base_discount_amount`: Discount value applied to order. `base_grand_total`: Final price paid by the customer on the order, after all taxes, shipping, and discounts are applied. Although the precise calculation is customizable, in general the `base_grand_total` is calculated as `base_subtotal` + `base_tax_amount` + `base_shipping_amount` + `base_discount_amount` - `base_gift_cards_amount` - `base_customer_balance_amount`. `base_subtotal`: Gross merchandise value of all items included in the order. Taxes, shipping, discounts and so on are not included. `base_tax_amount`: Tax value applied to order. `created_at`: Creation timestamp of the order, usually stored locally in UTC. Depending on your configuration in MBI, this timestamp may be converted to a reporting time zone in MBI that differs from your database time zone. The difference between Base Totals & Totals are in the customer's Currency vs your shop's Base Currency. Used for the currency switcher. |
+| Sales Order Shipping Properties | `shipping_method` - varchar(120), `shipping_description` - varchar(255), `shipping_amount` - decimal(20,4), `shipping_canceled` - decimal(20,4), `shipping_invoiced` - decimal(20,4), `shipping_refunded` - decimal(20,4), `shipping_tax_amount` - decimal(20,4), `shipping_tax_refunded` - decimal(20,4), `shipping_discount_amount` - decimal(20,4), `base_shipping_discount_amount` - decimal(20,4), `base_shipping_amount` - decimal(20,4), `base_shipping_canceled` - decimal(20,4), `base_shipping_invoiced` - decimal(20,4), `base_shipping_refunded` - decimal(20,4), `base_shipping_tax_amount` - decimal(20,4), `base_shipping_tax_refunded` - decimal(20,4), `can_ship_partially` - smallint(5), `can_ship_partially_item` - smallint(5), `shipping_discount_tax_compensation_amount` - decimal(20,4), `base_shipping_discount_tax_compensation_amnt` - decimal(20,4), `shipping_incl_tax` - decimal(20,4), `base_shipping_incl_tax` - decimal(20,4) | The Sales calculated shipping totals. `base_shipping_amount`: Shipping value applied to order. `shipping_address_id`: Foreign key associated with the `sales_order_address` table. Join to `sales_order_address`.`entity_id` to determine the shipping address details associated with the order. |
+| Sales Order Customer Properties | `customer_id` - int(10), `ext_customer_id` - varchar(32), `customer_is_guest` - smallint(5), `customer_note_notify` - smallint(5), `billing_address_id` - int(11), `shipping_address_id` - int(11), `customer_group_id` - int(11), `customer_email` - varchar(128), `customer_firstname` - varchar(128), `customer_lastname` - varchar(128), `customer_middlename` - varchar(128), `customer_prefix` - varchar(32), `customer_suffix` - varchar(32), `customer_taxvat` - varchar(32), `customer_dob` - datetime, `customer_gender` - int(11 | De-normalised / duplicate information data regarding the customer for a specific Sales Order. `customer_id`: Foreign key associated with the `customer_entity` table, if the customer is registered. Join to `customer_entity`.`entity_id` to determine customer attributes associated with the order. If the order was placed through guest checkout, this field will be NULL.`customer_email`: Email address of the customer placing the order. This will be populated in all situations, including orders processed through guest checkout.`customer_group_id`: Foreign key associated with the `customer_group` table. Join to `customer_group`.`customer_group_id` to determine the customer group associated with the order.`billing_address_id`: Foreign key associated with the `sales_order_address` table. Join to `sales_order_address`.`entity_id` to determine the billing address details associated with the order. The reason why this information is duplicated is for preservation, in case the customer changes their information / remove's their account. It shouldn't affect Sales going forward. Another reason is for read performance purposes, duplicating this data saves on extra relational queries. |
+| Sales / Cart Price Rules | `coupon_code` - varchar(255), `coupon_rule_name` - varchar(255), `applied_rule_ids` - varchar(128) | Used for [Sales / Cart Price Rules](#h.5wkclkkw15ho) (promotions) applied Rule IDs / Coupons. `coupon_code`: Coupon applied to order. If no coupon is applied, this field will be NULL |
+| [Magento Store Credit](https://docs.magento.com/user-guide/sales/store-credit.html&sa=D&ust=1609223266135000&usg=AOvVaw2LYfnf25YAttTGK2tfag24) (Magento commerce/enterprise only) | `base_customer_balance_amount` - decimal(20,4), `customer_balance_amount` - decimal(20,4), `base_customer_balance_invoiced` - decimal(20,4), `customer_balance_invoiced` - decimal(20,4), `base_customer_balance_refunded` - decimal(20,4), `customer_balance_refunded` - decimal(20,4), `bs_customer_bal_total_refunded` - decimal(20,4), `customer_bal_total_refunded` - decimal(20,4) | These are all the relevant columns for [Magento Store Credit](https://docs.magento.com/user-guide/sales/store-credit.html&sa=D&ust=1609223266137000&usg=`AOvVaw2e_OHq8R`-YZDd00RyPtjP2) (Magento commerce/enterprise only). Store credit is an amount that is restored to a customer account. Customers can use their store credit to pay for purchases, and administrators can use store credit for cash refunds. Gift card balances can be credited to the customer's account, instead of using the gift card code for future purchases. |
+| [Magento Giftcard Accounts](https://docs.magento.com/user-guide/catalog/product-gift-card-accounts.html&sa=D&ust=1609223266138000&usg=AOvVaw2D4ptMgaFMcQvyutR6fGJc) (Magento commerce/enterprise only) | `gift_cards` - text, `base_gift_cards_amount` - decimal(20,4), `gift_cards_amount` - decimal(20,4), `base_gift_cards_invoiced` - decimal(20,4), `gift_cards_invoiced` - decimal(20,4), `base_gift_cards_refunded` - decimal(20,4), `gift_cards_refunded` - decimal(20,4) | A gift card account is automatically created for each Gift Card that is purchased. The value of the gift card can then be applied toward the purchase of a product in your store. You can also create gift card accounts from the Admin as a promotion or service for customers. The gift card account number corresponds to the gift card code. The value in the Quote/Cart table will be the amount being redeemed. |
+| [Magento Gift Options](https://docs.magento.com/user-guide/sales/gift-options.html&sa=D&ust=1609223266140000&usg=`AOvVaw21htgCw_oXhOG62HHGZshh`) | `gift_message_id` - int(11) | `gift_message_id`: The foreign key linking `quote_item` to a [Gift Option](https://docs.magento.com/user-guide/sales/gift-options.html&sa=D&ust=1609223266141000&usg=`AOvVaw0rWU_BxoYRPSqDPbxz93eN`) |
+| [Magento Gift Wrapping](https://docs.magento.com/user-guide/sales/gift-wrap.html&sa=D&ust=1609223266141000&usg=`AOvVaw1mmETjVdBWtCNpOeS_87ge`) (Magento commerce/enterprise only) | `gw_id` - int(11), `gw_allow_gift_receipt` - int(11), `gw_add_card` - int(11), `gw_base_price` - decimal(12,4), `gw_price` - decimal(12,4), `gw_items_base_price` - decimal(12,4), `gw_items_price` - decimal(12,4), `gw_card_base_price` - decimal(12,4), `gw_card_price` - decimal(12,4), `gw_base_tax_amount` - decimal(12,4), `gw_tax_amount` - decimal(12,4), `gw_items_base_tax_amount` - decimal(12,4), `gw_items_tax_amount` - decimal(12,4), `gw_card_base_tax_amount` - decimal(12,4), `gw_card_tax_amount` - decimal(12,4), `gw_base_price_incl_tax` - decimal(12,4), `gw_price_incl_tax` - decimal(12,4), `gw_items_base_price_incl_tax` - decimal(12,4), `gw_items_price_incl_tax` - decimal(12,4), `gw_card_base_price_incl_tax` - decimal(12,4), `gw_card_price_incl_tax` - decimal(12,4), `gw_base_price_invoiced` - decimal(12,4), `gw_price_invoiced` - decimal(12,4), `gw_items_base_price_invoiced` - decimal(12,4), `gw_items_price_invoiced` - decimal(12,4), `gw_card_base_price_invoiced` - decimal(12,4), `gw_card_price_invoiced` - decimal(12,4), `gw_base_tax_amount_invoiced` - decimal(12,4), `gw_tax_amount_invoiced` - decimal(12,4), `gw_items_base_tax_invoiced` - decimal(12,4), `gw_items_tax_invoiced` - decimal(12,4), `gw_card_base_tax_invoiced` - decimal(12,4), `gw_card_tax_invoiced` - decimal(12,4), `gw_base_price_refunded` - decimal(12,4), `gw_price_refunded` - decimal(12,4), `gw_items_base_price_refunded` - decimal(12,4), `gw_items_price_refunded` - decimal(12,4), `gw_card_base_price_refunded` - decimal(12,4), `gw_card_price_refunded` - decimal(12,4), `gw_base_tax_amount_refunded` - decimal(12,4), `gw_tax_amount_refunded` - decimal(12,4), `gw_items_base_tax_refunded` - decimal(12,4), `gw_items_tax_refunded` - decimal(12,4), `gw_card_base_tax_refunded` - decimal(12,4), `gw_card_tax_refunded` - decimal(12,4) | These are all the relevant columns for [Magento Gift Wrapping](https://docs.magento.com/user-guide/sales/gift-wrap.html&sa=D&ust=1609223266148000&usg=AOvVaw3Ulr3t2G09fFJRoUTGOekm) (Magento commerce/enterprise only). Gift wrapping is available for any product that can be shipped, and can be offered for individual items or for the entire order. You can charge a separate price for each gift wrap design, and upload a thumbnail image of the design that appears as an option for the product in the cart. |
+| [Reward Points](https://docs.magento.com/user-guide/configuration/customers/reward-points.html&sa=D&ust=1609223266148000&usg=`AOvVaw0LilImF_EsloMambWkfgKG`) (Magento commerce/enterprise only) | `reward_points_balance` - int(11), `base_reward_currency_amount` - decimal(20,4), `reward_currency_amount` - decimal(20,4), `base_rwrd_crrncy_amt_invoiced` - decimal(20,4), `rwrd_currency_amount_invoiced` - decimal(20,4), `base_rwrd_crrncy_amnt_refnded` - decimal(20,4), `rwrd_crrncy_amnt_refunded` - decimal(20,4), `reward_points_balance_refund` - int(11) | These are all the relevant columns for [Reward Points](https://docs.magento.com/user-guide/configuration/customers/reward-points.html&sa=D&ust=1609223266150000&usg=AOvVaw2LFtQeIqyXBdbx0AvAqj2G) (Magento commerce/enterprise only) Or Loyalty Points. |
+
+
+![Magento Exam Information](./images/icon-info.png)[More information on the sales_order table at Magento DevDocs](https://docs.magento.com/mbi/data-analyst/data-warehouse-mgr/sales-flat-order-table.html&sa=D&ust=1609223266151000&usg=AOvVaw1BJAaPbIJMfll91v2qistl).
+
+![Magento Exam Information](./images/icon-info.png)The main thing to remember here is that Sales adhere to the [Service Contracts](#h.i0qq8aqgijv7) design pattern, therefore all the necessary models for customisation are available within the Api/ directory of the Magento_Sales module.
+
+![Magento Exam Question](./images/icon-question.png)**Describe how to modify order processing and integrate it with a third-party ERP system.**
+
+> There are several readily accessible touchpoints to integrate Magento orders with an external system.
+
+### ![Magento Section Chevron](./images/icon-chevron.png)REST API
+
+> Magento 2 includes an extensive API that provides access to orders. Specifically, the sales order repository has been made available through the API: /rest/V1/orders. See: http://devdocs.magento.com/swagger/index_22.html. The documentation provides information on how to filter for a specific subset of orders.The use case for this would be an external service that queries Magento for the latest orders. This service operates as a pull operation, retrieving orders from Magento, and pushing into the ERP.
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Events
+
+> Magento provides a number of events that indicate when an order is complete. For example, sales_order_place_after is triggered when the order has been placed.You can also use RabbitMQ (available in Magento Open Source as a module). If consistency is important, using a messaging system might not be the best approach. If the operation fails after being sent to the external system, the data in the two systems becomes inconsistent
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Creating An Integration Using A Queue Consumer
+
+> This is also a very vague question with many possible answers depending on the requirements of the ERP system / the project. However considering we are talking about ERP integration with eCommerce this would most likely go down the route of:
+
+*   Making entities such as Customers, Orders, Products accessible via a certain protocol in a certain format which is compatible with the ERP.
+*   Creating a scheduled / event based queue / command bus system that would automate syncing.
+
+> One way we can achieve these things (the Magento way) is by:
+
+1.  [Creating An Integration](#h.t252zlddzc3r)
+2.  [Creating A QueueConsumer](#h.il8ytp8imwo3)
+
+> See below for details:
+
+![Magento Exam Information](./images/icon-info.png)The below is for demonstration purposes only. Given this question is a big vague and there are many ways to achieve such a project, the following may not appear in the exam. Despite this however, Integrations and Consumers are now a core part of Magento.
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Integration
+
+> To make entities such as Customers, Orders, Products accessible via a certain protocol in a certain format can be achieved by creating an integration to access the Magento WebAPI which supports web services such as [REST (Representational State Transfer) and SOAP (Simple Object Access Protocol)](https://devdocs.magento.com/guides/v2.4/get-started/bk-get-started-api.html&sa=D&ust=1609223266154000&usg=AOvVaw366ATMR34Q6QtN0OpwIeYx) authenticating using [Web API authentication](https://devdocs.magento.com/guides/v2.4/get-started/authentication/gs-authentication.html&sa=D&ust=1609223266154000&usg=AOvVaw2kSAeIyx5BmQZs3cmglNMQ) / [OAuth based authentication](https://devdocs.magento.com/guides/v2.4/get-started/authentication/gs-authentication-oauth.html&sa=D&ust=1609223266154000&usg=AOvVaw147HFV2e16CD1P5Q5i4sYi) and can output in either XML or JSON formats.
+>
+> Create a [Data Patch](#h.fb7s5a4nvxv9):
+
+```php
+<?php
+
+namespace Magento\DummyModule\Setup\Patch\Data;
+
+use Magento\Integration\Model\Integration;
+use Magento\Framework\Setup\Patch\DataPatchInterface;
+use Magento\Framework\Setup\ModuleDataSetupInterface;
+use Magento\Framework\Setup\Patch\PatchRevertableInterface;
+use Magento\Integration\Model\ConfigBasedIntegrationManager;
+
+class DummyDataPatch implements DataPatchInterface, PatchRevertableInterface
+{
+    /**
+     * @var ConfigBasedIntegrationManager
+     */
+    private $integrationManager;
+
+    /**
+     * @param ConfigBasedIntegrationManager $moduleDataSetup
+     */
+    public function __construct(ConfigBasedIntegrationManager $integrationManager)
+    {
+        $this->integrationManager = $integrationManager;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function apply()
+    {
+        $integrations = [
+            'TestIntegration1' => [
+                Integration::EMAIL => 'test-integration1@magento.com',
+                Integration::ENDPOINT => 'http://endpoint.com',
+                Integration::IDENTITY_LINK_URL => 'http://www.example.com/identity',
+                'resources' => [
+                    'Magento_Customer::manage',
+                    'Magento_Customer::customer'
+                ]
+            ],
+            'TestIntegration2' => [
+                Integration::EMAIL => 'test-integration2@magento.com',
+                Integration::ENDPOINT => 'http://endpoint.com',
+                Integration::IDENTITY_LINK_URL => 'http://www.example.com/identity'
+            ]
+        ];
+        $this->integrationManager->processConfigBasedIntegrations($integrations);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public static function getDependencies()
+    {
+        return [];
+    }
+
+    public function revert()
+    {
+        // Revert operations here
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getAliases()
+    {
+        return [];
+    }
+}
+```
+
+#### `integration/config.xml`
+
+> In the following line from above:
+
+```php
+$this->integrationManager->processIntegrationConfig($integrations);
+```
+
+> `$integrations` must refer to your `etc/integration/config.xml` file, and the integration name value must be the same.
+>
+> The following example demonstrates a minimal config.xml file.
+
+```xml
+<integrations>
+        <integration name="TestIntegration">
+                <email>someone@example.com</email>
+                <endpoint_url>https://example.com</endpoint_url>
+                <identity_link_url>https://example.com/identity_link_url</identity_link_url>
+        </integration>
+</integrations>
+```
+
+#### `integration/api.xml`
+
+> The `etc/integration/api.xml` file defines which API resources the integration has access to.
+>
+> To determine which resources an integration needs access to, review the permissions defined in each module's `etc/acl.xml` file.
+>
+> In the following example, the test integration requires access to the following resources in the Sales module:
+
+```xml
+<integrations>
+        <integration name="TestIntegration">
+                <resources>
+                        <!-- To grant permission to Magento_Log::online, its parent Magento_Customer::customer needs to be declared as well-->
+                        <resource name="Magento_Customer::customer" />
+                        <resource name="Magento_Log::online" />
+                        <!-- To grant permission to Magento_Sales::reorder, all its parent resources need to be declared-->
+                        <resource name="Magento_Sales::sales" />
+                        <resource name="Magento_Sales::sales_operation" />
+                        <resource name="Magento_Sales::sales_order" />
+                        <resource name="Magento_Sales::actions" />
+                        <resource name="Magento_Sales::reorder" />
+                </resources>
+        </integration>
+</integrations>
+```
+
+### ![Magento Section Chevron](./images/icon-chevron.png)Creating A Queue Consumer
+
+> Magento provides the Message Queue Framework (MQF) for publishing messages to queues and creating consumers to receive them asynchronously. MQF supports MySql and RabbitMQ queue systems.
+>
+> A message queue requires 4 XML files in `<module_dir>/etc` folder:
+
+*   `communication.xml` - Defines aspects of the message queue system that all communication types have in common.
+*   `queue_consumer.xml` - Defines the relationship between an existing queue and its consumer.
+*   `queue_topology.xml` - Defines the message routing rules and declares queues and exchanges.
+*   `queue_publisher.xml` - Defines the exchange where a topic is published.
+
+#### `communication.xml`
+
+*   Define its datatype 'string'. This is the datatype for pushing any messages through Magento
+*   Declare handler class '`MyVendor\MyModule\Model\Queue\Consumer`' with 'process' method to handle input from the queue
+
+```xml
+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Communication/etc/communication.xsd">
+    <topic name="custom.queue.order" request="string">
+        <handler name="processAddOrderToQueue" type="MyVendor\MyModule\Model\Queue\Consumer" method="process" />
+    </topic>
+</config>
+
+```
+
+**`<topic>` element**
+| Attribute | Description |
+| --- | --- |
+| `name` | A string that uniquely identifies the topic. A topic name should be a series of strings that are separated by periods. The leftmost string should be the most general, and each string afterward should narrow the scope. For example, to describe actions for tending to pets, you might create names such as cat.white.feed and dog.retriever.walk. Wildcards are not supported in the communication.xml file.
+| `request` | Specifies the data type of the topic. |
+| `response` | Specifies the format of the response. This parameter is required if you are defining a synchronous topic. Omit this parameter if you are defining an asynchronous topic. |
+| `schema` | The interface that describes the structure of the message. The format must be `<module>\Api\<ServiceName>::<methodName>`. |
+
+**`<handler>` element**
+
+> The handler element specifies the class where the logic for handling messages exists and the method it executes.
+
+| Parameter | Description |
+| --- | --- |
+| `name` | A string that uniquely defines the handler. The name can be derived from the topic name if the handler is specific to the topic. If the handler provides more generic capabilities, name the handler so that it describes those capabilities. |
+| `type` | The class or interface that defines the handler. |
+| `method` | The method this handler executes. |
+| `disabled` | Determines whether this handler is disabled. The default value is false. |
+
+#### `queue_consumer.xml`
+
+> In this file, we define the consumer parameters. It's also possible to declare a handler class in this file.
+
+```xml
+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework-message-queue:etc/consumer.xsd">
+    <consumer name="custom.queue.order" queue="custom.queue.order" connection="db" maxMessages="5000" consumerInstance="Magento\Framework\MessageQueue\Consumer" handler="MyVendor\MyModule\Model\Queue\Consumer::process "/>
+</config>
+```
+
+**`<consumer>` element**
+
+| Attribute | Description |
+| --- | --- |
+| `name` (required) | The name of the consumer. |
+| `queue` (required) | Defines the queue name to send the message to. |
+| `handler` | Specifies the class and method that processes the message. The value must be specified in the format `<Vendor>\Module\<ServiceName>::<methodName>`. |
+| `consumerInstance` | The Magento class name that consumes the message |
+| `connection` | (For AMQP connections): The connection name must match the connection attribute in the `queue_topology.xml` file. Otherwise, the connection name must be db. |
+| `maxMessages` | Specifies the maximum number of messages to consume. |
+
+#### Consumer Handlers
+
+> A handler is a class and method that processes a message. Magento has two ways to define a handler for messages:
+
+1.  In the `<handler>` element of the module's `communication.xml` file
+2.  In the `handler=""` attribute of the module's `queue_consumer.xml` file
+
+> The following conditions determine how these handlers are processed:
+
+*   If the consumer in `queue_consumer.xml` does not have a consumerInstance parameter defined, then the system uses the default consumer: `Magento\Framework\MessageQueue\Consumer`. In this case, if the `<consumer>` element contains the handler attribute, then it will be used, and the `<handler>` element in communication.xml will be ignored.
+*   If the consumer in `queue_consumer.xml` has a `consumerInstance` defined, then the specific consumer implementation defines how the handler is used. Magento provides these consumers out-of-the-box:
+
+#### `queue_topology.xml`
+
+The `queue_topology.xml` file defines the message routing rules and declares queues and exchanges. It contains the following elements:
+
+```xml
+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework-message-queue:etc/topology.xsd">
+    <exchange name="magento-db" type="topic" connection="db">
+        <binding id="processAddOrderToQueueBinding" topic="custom.queue.order" destinationType="queue" destination="custom.queue.order "/>
+    </exchange>
+</config>
+```
+
+**`<exchange>` element**
+
+| Attribute | Description |
+| --- | --- |
+| `name` (required) | A unique ID for the exchange. |
+| `type` (required) | Specifies the type of exchange. Must be topic. |
+| `connection` (required) | For AMQP connections, a string that identifies the connection. For MySQL connections, the connection name must be db. |
+| `durable` | Boolean value indicating whether the exchange is persistent. Non-durable exchanges are purged when the server restarts. The default is true. |
+| `autoDelete` | Boolean value indicating whether the exchange is deleted when all queues have finished using it. The default is false. |
+| `internal` | Boolean value. If set to true, the exchange may not be used directly by publishers, but only when bound to other exchanges. The default is false. |
+
+**`<binding>` element**
+
+| Attribute | Description |
+| --- | --- |
+| `id` (required) | A unique ID for this binding. |
+| `topic` (required) | The name of a topic. You can specify an asterisk (*) or pound sign (#) as wildcards. These are described below the table. |
+| `destinationType` (required) | Must be `queue`. |
+| `destination` (required) | Identifies the name of a queue. |
+| `disabled` | Determines whether this binding is disabled. The default value is false. |
+| `internal` | Boolean value. If set to true, the exchange may not be used directly by publishers, but only when bound to other exchanges. The default is false. |
+
+> Example topic names that include wildcards:
+
+| Attribute | Description | Matching Example Topics | Example non-matching topics |
+| --- | --- | --- | --- |
+| `*.*.*` | Matches any topic that contains exactly two periods. |`mytopic.createOrder.success`, `mytopic.updatePrice.item1` | `mytopic.createOrder`, `mytopic.createOrder.success.true` |
+| `#` | Matches any topic name. | `mytopic`, `mytopic.createOrder.success`, `this.is.a.long.topic.name` | N/A |
+| `mytopic.#` | Matches any topic name that begins with mytopic and has a period afterward. | `mytopic.success`, `mytopic.createOrder.error` | - |
+| `*.Order.#` | There must be one string before .Order. There can be any number of strings (including 0) after that. | `mytopic.Order`, `mytopic.Order.Create`, `newtopic.Order.delete.success` | - |
+
+**`<arguments>` element**
+
+> The arguments element is an optional element that contains one or more argument elements. These arguments define key/value pairs that are passed to the broker for processing. Each argument definition must have the following parameters:
+
+| Attribute | Description |
+| --- | --- |
+| `name` | The parameter name |
+| `type` | The data type of the value |
+
+> The following illustrates an arguments block:
+
+```xml
+<arguments>
+        <argument name="warehouseId" xsi:type="int">1</argument>
+        <argument name="carrierName" xsi:type="string">USPS</argument>
+</arguments>
+```
+
+#### `queue_publisher.xml`
+
+> Publishers
+>
+> Send a message to a message bus without knowing who is interested in the message.
+
+> Subscribers
+>
+> Listen to the message by "subscribing". The pattern is normally used as a one-to-many broadcast of messages, but it can be used as many-to-many, if appropriate.
+> The queue_publisher.xml file defines which connection and exchange to use to publish messages for a specific topic.
+>
+> Example setup of `queue_publisher.xml`
+
+```xml
+<?xml version="1.0"?>
+<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework-message-queue:etc/consumer.xsd">
+    <publisher topic="custom.queue.order">
+        <connection name="db" exchange="magento-db" />
+    </publisher>
+</config>
+```
+**``<publisher>`` element**
+
+| Attribute | Description |
+| --- | --- |
+| `topic` (required) | The name of the topic. |
+| `disabled` | Determines whether this queue is disabled. The default value is false. |
+
+
+**`<connection>` element**
+
+| Attribute | Description |
+| --- | --- |
+| `name` (required) | (For AMQP connections): The connection name must match the connection attribute in the queue_topology.xml file. Otherwise, the connection name must be db. If you omit the `<connection>` element, the default connection of amqp will be used. |
+| `exchange` | The name of the exchange to publish to. The default system exchange name is magento. If you omit the `<connection>` element, the default exchange magento will be used. |
+| `disabled` | Determines whether this queue is disabled. The default value is false. |
+
+![Magento Exam Information](./images/icon-info.png)You cannot enable more than one publisher for each topic.
+
+#### Publisher Class
+
+> In our example. Since we're using Mysql as queue systems, messages are stored in Magento's database in tables:
+
+*   `queue` - This table manages queues.
+*   `queue_message` - This table stores messages.
+*   `queue_message_status` - manages the message queue workload
+
+> To Publish (send) a message to the Message Bus you must inject the following interface into your class (be that an [Observer](#h.y2lezqicnwxl) or [Plugin](#h.nc1ow1wmf2km) etc):
+
+`Magento\Framework\MessageQueue\PublisherInterface`
+
+```php
+$this->_publisher->publish(
+        'custom.queue.order',
+        $this->_json->serialize($rawData)
+);
+```
+
+#### Consumer (Subscriber) Class
+
+```php
+<?php
+
+namespace MyVendor\MyModule\Model\Queue;
+
+/**
+ * Class Consumer
+ * @package MyVendor\MyModule\Model\Queue
+ */
+class Consumer
+
+{
+    /** @var Magento\Framework\Serialize\Serializer\Json */
+    protected $_json;
+
+    /**
+     * @param string $orders
+     */
+    public function process($orders)
+    {
+        try {
+            $this->execute($orders);
+        } catch (\Exception $e) {
+            $errorCode = $e->getCode();
+            $message = __('Something went wrong while adding orders to queue');
+            $this->_notifier->addCritical(
+                $errorCode,
+                $message
+            );
+            $this->_logger->critical($errorCode . ": " . $message);
+        }
+    }
+
+    /**
+     * @param $orderItems
+     *
+     * @throws LocalizedException
+     */
+    private function execute($orderItems)
+    {
+        $orderCollectionArr = [];
+        /** @var \MyVendor\MyModule\Model\Queue $queue */
+        $queue = $this->_queueFactory->create();
+        $orderItems = $this->_json->unserialize($orderItems);
+
+        if (is_array($orderItems)) {
+            foreach ($orderItems as $type => $orderId) {
+                $orderCollectionArr[] = [
+                    'type' => 'order',
+                    'entity_id' => $orderId,
+                    'priority' => 1,
+                ];
+            }
+
+            $queue->deleteQueueByType($this->_type);
+            $queue->enqueueMultiRecords($orderCollectionArr);
+        }
+    }
+}
+```
+
+Ensure the following is enable in your env.php to get Queue Consumers working:
+
+```php
+'cron' => [
+        'enabled' => 1
+],
+'cron_consumers_runner' => [
+        'cron_run' => true,
+        'max_messages' => 10000,
+        'consumers' => [] // Shorthand for enable all consumers
+]
+ ```
+
+> Aside from running via cron, consumers can be executed with the following command:
+
+```bash
+php bin/magento queue:consumers:start [--max-messages=<value>] [--batch-size=<value>] [--single-thread] [--area-code=<value>] <consumer_name>
+```
+
+![Magento Exam Information](./images/icon-info.png)More information available at [Magento DevDocs](https://devdocs.magento.com/guides/v2.4/extension-dev-guide/message-queues/config-mq.html%23communicationxml&sa=D&ust=1609223266220000&usg=AOvVaw1acuwyN6vkI2Ecl-AWUsMJ)
+
+![Magento Exam Question](./images/icon-question.png)**How would you add new states and statuses for an order?**
+
+> In addition to the preset order status settings, you can create custom order status settings of your own, assign them to order states, and set a default order status for order states. For example, you might need a custom order status such as "packaging", "backordered", or a status that is specific to your needs. You can create a descriptive name for the custom status and assign it to the associated order state in the workflow.
+>
+> **Admin > Stores > Order Status**
+
+![](./images/Magento2-Certification-Exam-Notes-Detailed-Insight-Order-Status.png)
+
+![Magento Exam Information](./images/icon-info.png)More information available at [Magento DevDocs](https://docs.magento.com/user-guide/sales/order-status-custom.html&sa=D&ust=1609223266222000&usg=AOvVaw26BMukpJ5JGb1AZw-NExB9)
+
+![Magento Exam Question](./images/icon-question.png)**What is the difference between Order State & Order Status?**
+
+> The notions Order "`state`" & Order "`status`" are usually mixed up since their names and functions are quite similar.
+>
+> An Order "state" is a position of an order in the current processing flow.
+>
+> See table below for Magento has states Magento\Sales\Model\Order:
+
+```php
+const STATE_NEW = 'new';
+const STATE_PENDING_PAYMENT = 'pending_payment';
+const STATE_PROCESSING = 'processing';
+const STATE_COMPLETE = 'complete';
+const STATE_CLOSED = 'closed';
+const STATE_CANCELED = 'canceled';
+const STATE_HOLDED = 'holded';
+const STATE_PAYMENT_REVIEW = 'payment_review';
+```
+
+> Each Magento Order "state" can have one or more Order "statuses" assigned to it.
+>
+> This makes processing easier and helps to add some flexibility to order. For example, a "Pending Payment" order state can have the following order statuses:
+
+* Pending Payment Paypal
+* Pending Payment Card
+* Pending Payment Store Credit
+* and the like.
+
+> Default Order Statuses Table
+
+| Order Status | Status Code | Description |
+| --- | --- | --- |
+| Processing | `processing` | Processing means that orders have either been invoiced or shipped, but not both. |
+| Suspected Fraud | `fraud` | Dodgy as |
+| Pending Payment | `pending_payment` | Order created without invoice |
+| Payment Review | `payment_review` | In Payment Review Checkout Step |
+| Pending | `pending` | Pending orders are brand new orders that have not been processed. Typically, these orders need to be invoiced and shipped. |
+| On Hold | `holded` | Manual action from the user. Orders placed on hold must be taken off hold before continuing any further actions. |
+| Open | `STATE_OPEN` | User has created a quote and proceeds through the checkout Order just created, not saved. |
+| Complete | `complete` | Order fulfilled. Orders marked as complete have been invoiced and have shipped. |
+| Closed | `closed` | Closed orders are orders that have had a credit memo assigned to it and the customer has been refunded for their order. |
+| Canceled | `canceled` | Cancelled orders should be used if orders are cancelled or if the orders have not been paid for. |
+| PayPal Canceled Reversal | `paypay_canceled_reversal` |  |
+| Pending PayPal | `pending_paypal` | Pending PayPal orders are brand new orders that have not been cleared by PayPal. [...] |
+| PayPal Reversed | `paypal_reversed` | |
+
+![Magento Exam Question](./images/icon-question.png)**How do you change the behavior of existing states and statuses?**
+
+![Magento Section Chevron](./images/icon-chevron.png)Via Admin
+
+> **Admin > Stores > Order Status > Assign Status**
+
+![](./images/Magento2-Certification-Exam-Notes-Detailed-Insight-Order-Status-Assign.png)
+
+![Magento Exam Information](./images/icon-info.png)More information available at [Magento DevDocs](https://docs.magento.com/user-guide/sales/order-status-custom.html%23to-edit-an-existing-order-status&sa=D&ust=1609223266236000&usg=AOvVaw24EjvZ7avcHc5vh6xEWa7r)
+
+![Magento Section Chevron](./images/icon-chevron.png)Programmatically
+
+> By manipulating the "`state`" and "`status`" properties of the following interface:
+>
+> `Magento\Sales\Api\Data\OrderInterface $order`;
+>
+> Then saving using the following repository:
+>
+> `Magento\Sales\Api\OrderRepositoryInterface $orderRepository`;
+>
+> Example:
+
+```php
+$order->setState(\Magento\Sales\Model\Order::STATE_PROCESSING);
+$order->setStatus('processing');
+$order->addStatusToHistory($order->getStatus(), 'Custom Message');
+$orderRepository->save($order);
+```
+
+![Magento Exam Question](./images/icon-question.png)**Describe how to modify order processing flow.**
+
+> To modify order processing, you can use an [Observer](#h.y2lezqicnwxl) or [Plugin](#h.nc1ow1wmf2km)
+>
+> Plugin
+>
+> You can create a [Plugin](#h.nc1ow1wmf2km) for one of the methods of the following Api interface:
+
+```php
+Magento\Quote\Api\CartManagementInterface::placeOrder
+Magento\Quote\Api\CartManagementInterface::submitQuote
+```
+
+> Observer
+>
+> Or you can create an [Observer](#h.y2lezqicnwxl) for one of the following events:
+
+*   `sales_model_service_quote_submit_before`
+*   `sales_model_service_quote_submit_success`
+*   `sales_model_service_quote_submit_failure`
+*   `checkout_submit_before`
+*   `checkout_submit_all_after`
+
+![Magento Exam Question](./images/icon-question.png)**Describe how to customize invoices. How would you customize invoice generation, capturing, and management?**
+
+> To create/customise an invoice, use the interface:
+>
+> `Magento\Sales\Api\InvoiceManagementInterface`
+>
+> And it's concrete implementation method prepareInvoice:
+>
+> `Magento\Sales\Model\Service\InvoiceService::prepareInvoice`
+>
+> `Magento\Sales\Model\Service\InvoiceService::prepareInvoice` method, which in turn uses `Magento\Sales\Model\Order\Invoice`. In order to add your logic to the invoice creation process, you can use one of the following events to create an [Observer](#h.y2lezqicnwxl):
+
+*   `sales_order_invoice_pay`
+*   `sales_order_invoice_cancel`
+*   `sales_order_invoice_register`
+
+
+> An invoice can have one of the three states:
+
+* `STATE_OPEN`
+* `STATE_PAID`
+* `STATE_CANCELED`
+
+> There are 2 types of invoice:
+
+1.  Online Invoice - Online invoice calls the capture method for payment, which in turn can send a request to the payment system.
+2.  Offline Invoice - Offline invoice changes the payment information only at the Magento side.
+
+![Magento Exam Question](./images/icon-question.png)**Describe refund functionality in Magento. Which refund types are available, and how are they used?**
+
+> Credit Memo are responsible in Magento 2 for refunding orders, allowing to return the order partially or completely. Also,
+>
+> There are 2 types of refund:
+
+1.  Online - While online refund sends a query to the payment system. PayPal for example.
+2.  Offline - An offline refund is performed on Magento side and does not send any requests to the payment processing system.
+
+> A refund can be offline and online (depending on the order type). By default, they are mostly always offline as the money is handled elsewhere / the client would usually have an ERP system to manage refunds that can integrate into Magento.
+>
+> An example of a void transaction:
+
+```php
+<?php
+
+protected function _void($isOnline, $amount = null, $gatewayCallback = 'void')
+{
+    $order = $this->getOrder();
+    $authTransaction = $this->getAuthorizationTransaction();
+    $this->setTransactionId(
+        $this->transactionManager->generateTransactionId($this, Transaction::TYPE_VOID, $authTransaction)
+    );
+    $this->setShouldCloseParentTransaction(true);
+
+    // Attempt to void
+    if ($isOnline) {
+        $method = $this->getMethodInstance();
+        $method->setStore($order->getStoreId());
+        $method->{$gatewayCallback}($this);
+    }
+}
+```
+![Magento Exam Information](./images/icon-info.png)The Magento 2 Enterprise/Commerce Edition also allows the refund into Store Credits, with which a customer can later pay for other items in this store.
\ No newline at end of file
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diff --git a/README.md b/README.md
index e1339d0..df3b986 100644
--- a/README.md
+++ b/README.md
@@ -1,48 +1,75 @@
-# Overview
-
-Magento 2 Certified Professional Developer notes
-
-# 1. Topics
-
-1. 18% 1 - Magento Architecture and Customization Techniques  (11 questions)
-      - modules, config, di, plugins, events, cron, cli, cache
-2. 12% 2 - Request Flow Processing                            (7 questions)
-      - modes, front contr., url, rewrite, action contr., response, routes, 404, layout, page layout
-3. 10% 3 - Customizing the Magento UI                         (6 questions)
-      - theme, template, block, block cache, JS, UI component (briefly)
-4. 7% 4 - Working with Databases in Magento                  (4 questions)
-      - repository, api data class, search criteria, table, load/save, collection, select, migration 
-5. 8% 5 - Using the Entity-Attribute-Value (EAV) Model       (5 questions)
-      - hierarchy, storage, load/save, attributes, frontend/source/backend
-6. 10% 6 - Developing with Adminhtml                          (6 questions)
-      - form, grid, system.xml, menu, acl
-7. 12% 7 - Customizing the Catalog                            (7 questions)
-      - product types, price, price render, category, catalog rules
-8. 13% 8 - Customizing the Checkout Process                   (8 questions)
-      - cart rule, add to cart, quote totals, product type render, shipping method, payment method
-      * normal/wishlist/reorder/quote merge
-9. 5% 9 - Sales Operations                                   (3 questions)
-      - order processing, status, invoice, refund
-10. 5% 10 - Customer Management                              (3 questions)
-      - my account, customer extension attributes, address, customer group, tax
-
-
-### 1.2 Magento 2 Certified Professional Developer
+![Magento 2 Exam Notes & Detailed Insight](./images/icon-magento-logo.png)
+
+Magento 2 Exam Notes & Detailed Insight
+=======================================
+
+Contents
+--------
+
+### Modules
+
+Modules & there Approximate percentage covered in the test
+
+* [1. Magento Architecture & Customization Techniques](./1.Magento-Architecture-Customisation-Techniques.md) 18%
+* [2. Request Flow Processing](./2.Magento-Request-Flow-Processing.md) 12%
+* [3. Customizing the Magento UI](./3.Magento-Customising-The-UI.md) 10%
+* [4. Working with Databases in Magento](./4.Magento-Working-With-Databases.md) 7%
+* [5. Using the Entity-Attribute-Value (EAV) Model](./5.Magento-Using-Entity-Attribute-Value-Model.md) 8%
+* [6. Developing with Adminhtml](./6.Magento-Developing-With-Adminhtml.md) 10%
+* [7. Customizing the Catalog](./7.Magento-Customising-The-Catalogue.md) 12%
+* [8. Customizing the Checkout Process](./8.Magento-Customising-The-Checkout-Process.md) 13%
+* [9. Sales Operations](./9.Magento-Sales-Operations.md) 5%
+* [10. Customer Management](./10.Magento-Customer-Management.md) 5%
+* [11. Multi-store & Multi-website](./11.Magento-Multi-Store-Multi-Website-Scopes.md) [Bonus]
+* [12. Index Management](./12.Magento-Index-Management.md) [Bonus]
+
+| Key | Description
+| --- | --- |
+| ![question](./images/icon-question.png) | Question mark icons such as these will appear throughout this document to highlight possible questions that may appear in the exam. The Exam is a multiple choice whereas these questions are not. You won't be expected to remember them word for word. |
+| ![info](./images/icon-info.png) | Information icons such as these will appear throughout that aim to elaborate on the specifics of what is required to understand the relative question for the exam. |
+| ![chevron](./images/icon-chevron.png) | Chevron represents a subsection under a question. |
+| ![warning](images/icon-warning.png) | Heed any warnings or possible deprecation. |
+
+
+
+### AD0-E703 Adobe Magento Commerce Developer Expert (Formerly Magento 2 Certified Professional Developer)
 
 + 60 Multiple Choice items
-+ 90 minutes to complete the exam
++ 120 minutes to complete the exam
 + A score of 64% or higher is needed to pass the Magento 2 Certified Professional Developer exam
-+ Based on Magento Open Source (2.2) and Magento Commerce (2.2), but applicable to those using any version of Magento 2.
++ Based on Adobe Magento Open Source / Commerce (Enterprise) version 2.3, but applicable to those using any version of Magento 2.
+
+### Topics
+
+| % | Topic | Questions | Modules |
+| --- | --- | --- | --- |
+| 18% | 1 - Magento Architecture and Customization Techniques | (11 questions) | modules, config, di, plugins, events, cron, cli, cache |
+| 12% | 2 - Request Flow Processing | (7 questions) | modes, front controller, url, rewrite, action controller, response, routes, 404, layout, page layout |
+| 10% | 3 - Customizing the Magento UI | (6 questions) | theme, template, block, block cache, JS, UI component (briefly) |
+| 7% | 4 - Working with Databases in Magento | (4 questions) | repository, api data class, search criteria, table, load/save, collection, select, migration |
+| 8% | 5 - Using the Entity-Attribute-Value (EAV) Model | (5 questions) | hierarchy, storage, load/save, attributes, frontend/source/backend |
+| 10% | 6 - Developing with Adminhtml | (6 questions) | form, grid, system.xml, menu, acl |
+| 12% | 7 - Customizing the Catalog | (7 questions) | product types, price, price render, category, catalog rules |
+| 13% | 8 - Customizing the Checkout Process | (8 questions) | cart rule, add to cart, quote totals, product type render, shipping method, payment method (normal/wishlist/reorder/quote merge) |
+| 5% | 9 - Sales Operations | (3 questions) | order processing, status, invoice, refund |
+| 5% | 10 - Customer Management | (3 questions) | my account, customer extension attributes, address, customer group, tax |
+
 
-# 2. Resources
+Resources
+--------
 
-## 2.1. Links
+References & Links:
 + [Magento 2 Certified Professional Developer](https://u.magento.com/magento-2-certified-professional-developer)
 + [Magento 2.2 Developer Documentation](http://devdocs.magento.com/)
 + [Markdown Cheatsheet](https://github.com/adam-p/markdown-here/wiki/Markdown-Cheatsheet)
 + [Markdown Cheatsheet RU](https://github.com/sandino/Markdown-Cheatsheet)
 + [Swiftotter Study Guide](https://swiftotter.com/technical/certifications/magento-2-certified-developer-study-guide)
++ [Belvg - Magento 2 Certified Professional Developer Guide](https://belvg.com/tutorial/magento-2-certified-professional-developer-guide&sa=D&ust=1609223264400000&usg=AOvVaw3wfSbNPHKwUPDf_GWWY6T4)
++ [Magento DevDocs - Backend Dev Guide](https://devdocs.magento.com/guides/v2.3/extension-dev-guide/bk-extension-dev-guide.html&sa=D&ust=1609223264400000&usg=AOvVaw3D424pQdrMHBTCNLGC8aTO)
++ [Magento DevDocs - Frontend Dev Guide](https://devdocs.magento.com/guides/v2.3/frontend-dev-guide/bk-frontend-dev-guide.html&sa=D&ust=1609223264401000&usg=AOvVaw1JS0jwvA_O3qk-en_RD83l)
++ [Magento DevDocs - UI Components Dev Guide](https://devdocs.magento.com/guides/v2.3/ui_comp_guide/bk-ui_comps.html&sa=D&ust=1609223264402000&usg=AOvVaw3o33OMyCr5fWmJMutRw6Jw)
++ [Magento DevDocs - Javascript Dev Guide](https://devdocs.magento.com/guides/v2.3/javascript-dev-guide/bk-javascript-dev-guide.html&sa=D&ust=1609223264402000&usg=AOvVaw1jev8HcRQ-LtGrWqzET33Q)
 
-## 2.2. Credits
+## Credits
 
-Inspired by https://github.com/colinmurphy/magento-exam-notes
+Inspired by https://github.com/colinmurphy/magento-exam-notes
\ No newline at end of file
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