Last updated January 27, 2017
Module Development8.9.x/9.0.x

Hooks allow module developers to execute custom code at key moments during Drupal's request processing life cycle. They can be used to react to actions or conditions, alter forms and existing configuration, and extend Drupal in various ways. Knowing how to implement a hook is an essential skill for any Drupal developer.

In this tutorial we'll walk through the process of locating the documentation for a specific hook, and then implementing it. All hooks are implemented in the same way, so once you know how to implement one, you'll be able to implement any.