Drupal  8.3.5
APl Documentation
Extending and altering Drupal

Overview of extensions and alteration methods for Drupal.

Types of extensions

Drupal's core behavior can be extended and altered via these three basic types of extensions:

Alteration methods for modules

Here is a list of the ways that modules can alter or extend Drupal's core behavior, or the behavior of other modules:

*.info.yml files

Extensions must each be located in a directory whose name matches the short name (or machine name) of the extension, and this directory must contain a file named machine_name.info.yml (where machine_name is the machine name of the extension). See parse() for documentation of the format of .info.yml files.