Drupal is a free and open-source content management framework and content management system (CMS) built on PHP and MySQL. It can be used to create portals, blogs, e-commerce sites, and other types of content-driven websites and applications. Drupal is highly customizable through a plugin architecture and framework that allows users to manage and organize content in a database and control access, permissions and workflow. It has an active community that contributes code and documentation and organizes events like DrupalCamps to support the project.