API reference for Drupal 9

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Welcome to the Drupal API Documentation!

This site is an API reference for Drupal, generated from comments embedded in the source code. More in-depth documentation can be found at https://www.drupal.org/developing/api.

Here are some topics to help you get started developing with Drupal.

Essential background concepts

• Object-oriented conventions used in Drupal
• Extending and altering Drupal
• Security and best practices
• Types of information in Drupal

User interface

• Menu entries, local tasks, and other links
• Routing API and page controllers
• Forms
• Blocks
• Ajax

Storing and retrieving data

• Entities
• Fields
• Configuration API
• State API
• Views
• Database abstraction layer

Other essential APIs

• Plugins
• Services and the Dependency Injection Container
• Events
• Internationalization
• Caching
• Utility classes and functions
• User accounts, permissions, and roles
• Render API
• Theme system
• Update API
• Migration

Additional topics

• Batch API
• Queue API
• Typed Data
• Automated tests
• PHP Runtime Assert Statements
• Integrating third-party applications

Further information

• Examples project (sample modules)
• API change notices
• Drupal API longer references