Drupal 8  8.0.2
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.