You are adding an entry to the backend menu. To do so you open a core etc/adminhtml/menu.xml file as a reference. In the file you see the node:

What is the result of specifying resource="Magento_Catalog::catalog"?

You are working on a project that contains a million SKUs. The merchant has requested the product view page to have a custom color schema and page layout depending on the product price range.
How do you implement this, keeping simplicity in mind?

A module MyModule needs to send notifications to customers only when the account was modified from a mobile app using the REST web APIs.
You decided to implement an observer for customer_save_after_data_object event.
In which file do you declare the observer?

How do you persist an entity to the database?

What is a valid use case for an around plugin?