The Drupal open source content management system (CMS), which is licensed under the GNU general public license (GPL), provides very high-level functionality for creating and managing large Web sites and corporate portals. The product features very good capabilities for handling large and complex repositories of content and can be highly customized to meet a wide variety of needs. Drupal can run on most systems that can run PHP, including Linux and Windows systems. With Drupal 7, the CMS adds a new user interface designed to cut down on the complexity of most common management tasks within the CMS. Drupal 7 has also improved the ability to add modules and keep them up-to-date, as well as improved tools for adding and changing themes to adjust the look and feel of Web sites.