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Drupal
Drupal ( /ˈdruːpəl/) is a free and open-source content management system (CMS) and content management framework (CMF) written in PHP and distributed under the GNU General Public License.[2][3][4] It is used as a back-end system for at least 1.5% of all websites worldwide[5][6] ranging from personal blogs to corporate, political, and government sites including whitehouse.gov and data.gov.uk.[7] It is also used for knowledge management and business collaboration.