Drupal (pronounced /ˈdruːpəl/) is a free and open source modular content management system (CMS) written in the programming language PHP. A CMS is a tool used by Web administrators to automatically track online visitors and prepare customized content for consumption, usually as HTML-based Web pages. Drupal, like many modern CMSs, allows the system administrator to customize the content and display of the Web site with little or no programming.
Drupal runs in many environments, including Windows, Mac OS X, Linux, FreeBSD, and any platform that supports either the Apache (version 1.3+), or IIS (version IIS5+) Web server and the PHP language (version 4.3.3+). Drupal requires a database such as MySQL or PostgreSQL to store content and settings. (Requirements are available at Drupal's web site).
As of October 17, 2007, the current version of Drupal is 5.3. The third beta release of Version 6.0, which has reached a feature freeze, occurred on November 21, 2007.