Drupal /ˈdruːpəl/ is a free and open-source content-management framework written in PHP and distributed under the GNU General Public License. It is used as a back-end framework for at least 2.1% of all Web sites worldwide ranging from personal blogs to corporate, political, and government sites. It is also used for knowledge management and business collaboration.The standard release of Drupal, known as Drupal core, contains basic features common to content management systems.