Modules

Just about everything in Drupal revolves around the concept of modules, which are files that contain PHP code and a set of functionalities that Drupal knows how to use. All of the administrative- and end-user-facing functionality in Drupal, from fundamental features such as the ability to log in or create content to dynamic photo galleries and complex voting systems, comes from modules. Some examples of modules are the Contact module, which enables a site-wide contact form, and the User module, which handles user authentication and permission checking. In other CMS applications, modules are also referred to as plug-ins or extensions.

There are two types of modules: “core” modules, which are included with Drupal itself, and “contributed” modules, which are provided by the Drupal community and can be separately downloaded and enabled. Apart from a few required core modules, all modules can be turned on or off depending on your website’s precise needs.