Classes

Plugins extend or alter existing parts of a system. In Drupal, plugins are used for defining blocks, field types...

Modifying other modules.

Drupal development preaches "Don't hack core". This is a principal that your application logic...

Bootstrapping is the process software uses to load itself, as in pulling yourself up by the bootstraps. For example...

Modules can define package dependencies in their own composer.json.

 { "name": "drupal/views_sql_query_formatter", "type...

A service is a class that has functions to use in another class or module. This provides an interface for developers to...

These are built in classes and functions to handle some routine things.

core/lib/Drupal/Component/Utility/

Html

 cleanCs...

Once you've learned object oriented concepts, you're ready to approach a big project like Drupal. This class will...

As you program, you will have questions about the classes you're working with. Learning how to browse the code and...

HTML Cache

When a server sends an HTML page, it can set caching instructions in the header that tell your browser how...

Create custom modules with the Drupal API.

It's helpful to think of the existing core and contrib code as examples of...