Drupal is an open-source CMS created by Dries Buytaert in 2001. It is known for its powerful taxonomy and ability to handle complex content types and relationships. Drupal is highly customizable and secure, often used for enterprise-level websites. Its modular architecture allows developers to extend its functionality through a vast array of modules. Despite its steep learning curve, Drupal offers unmatched flexibility for building complex websites. It is an excellent choice for developers looking for a highly scalable and customizable platform.