Note

The above definitions, however, can also benefit from further explanation. For those interested in additional reading and background, the following links provide a more detailed overview, and some background information:

PHP: http://php.net/

Web content management system, defined: http://en.wikipedia.org/wiki/Web_content_management_system

The GPL, or the Gnu Public License: http://www.gnu.org; Drupal is covered under version 2 of the GPL: http://www.gnu.org/licenses/old-licenses/gpl-2.0.html

Web development framework, defined: http://en.wikipedia.org/wiki/Web_application_framework

Background information on Open Source: http://www.opensource.org

Overview section, from the Drupal handbook: http://drupal.org/node/21951