A module is a type of software package that extends the functionality of the Drupal content management system (CMS). Modules are written in the PHP programming language and are typically distributed as part of a Drupal distribution or as a stand-alone package. Modules can be used to add new features and functionality to a Drupal website, such as custom content types, user roles, and search engine optimization (SEO) tools. They can also be used to modify existing features, such as changing the way content is displayed or adding new fields to existing content types. Modules are managed through the Drupal administrative interface, where they can be enabled, disabled, and configured.
Modules are typically developed by third-party developers, but they can also be created by Drupal users. Modules can be downloaded from the Drupal website or from other sources, such as GitHub. Once a module is downloaded, it must be installed and enabled in order to be used. Once enabled, the module can be configured to meet the needs of the website.