Drupal is a free and open source content management system built using PHP. It began in 2001 and has grown to be one of the most popular frameworks, powering over 7 million websites. Drupal offers high customization through its thousands of modules for features like galleries, menus, analytics, and ecommerce, as well as themes. While powerful, Drupal is known for a steep learning curve for beginners unfamiliar with web programming. New releases aim to improve the user experience for all skill levels.