Drupal is a free and open-source content management system (CMS) written in PHP that allows users to manage and publish content on the web without needing to know HTML or web programming. It is used by over 1% of websites worldwide and by sites such as WhiteHouse.gov. Drupal provides tools for adding, editing, organizing, and publishing content on a website through an intuitive graphical interface. Users can customize Drupal through thousands of free modules and themes available online.