1. module.xml

    • This is the only required configuration file. It specifies the current module’s version and the module loading order.

  2. acl.xml

    • This defines the permissions for accessing protected resources.

  3. config.xml

      • This loads in default configuration in to Store > Configuration. This is also where configuration entries can be marked as encrypted (password).

    1. crontab.xml

      • This identifies actions that are to occur on a schedule.

    2. di.xml

        • This configures dependency injection for your module. This is perhaps the most frequently used file when customizing Magento. Here plugins are defined, class substitutions performed, concrete classes are specified for interfaces, virtual types set up, and constructor arguments can be specified or modified.
        • It is very important to familiarize yourself with the capabilities of this file.

        1. 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.

        2. events.xml

          • This file registers event listeners. This file can often be put into a specific area.

        3. indexer.xml

          • Configures Magento indexers.

        4. adminhtml/menu.xml

          • Configures the menu in the adminhtml area.

        5. mview.xml

            • Triggers a type of event when data is modified in a database column (materialized views). This is most often used for indexing.