Drupal is an open-source content management system (CMS) written in PHP that allows users to collaboratively create, edit, publish and manage various kinds of digital content. It provides a user interface for adding and editing content, and helps manage complexity by providing a means for collaboration. Drupal uses a modular architecture that separates functionality into modules and themes that can be managed through the user interface. Content in Drupal is organized into nodes that reside in content regions and can include other blocks like views, widgets and menus.