Drupal is a free and open-source content management system

Content management system

A content management system is a system providing a collection of procedures used to manage work flow in a collaborative environment. These procedures can be manual or computer-based...

 (CMS) and content management framework

Content management framework

A content management framework is an application programming interface for creating a customized content management system . The relationship between a CMF and a CMS can be illustrated by the following analogy:...

 (CMF) written in PHP

PHP

PHP is a general-purpose server-side scripting language originally designed for web development to produce dynamic web pages. For this purpose, PHP code is embedded into the HTML source document and interpreted by a web server with a PHP processor module, which generates the web page document...

 and distributed under the GNU General Public License. It is used as a back-end system for at least 1.5% of all websites

World Wide Web

The World Wide Web is a system of interlinked hypertext documents accessed via the Internet...

 worldwide ranging from personal blog

Blog

A blog is a type of website or part of a website supposed to be updated with new content from time to time. Blogs are usually maintained by an individual with regular entries of commentary, descriptions of events, or other material such as graphics or video. Entries are commonly displayed in...

s to corporate, political, and government sites including whitehouse.gov

Whitehouse.gov

Whitehouse.gov is the official website of the White House and is owned by the United States government. Launched in October 1994, it contains general American history information, as well as current news pertaining to the President, press briefings, proclamations, executive orders, and any speeches...

 and data.gov.uk

Data.gov.uk

data.gov.uk is a UK Government project to open up almost all non-personal data acquired for official purposes for free re-use. Sir Tim Berners-Lee and Professor Nigel Shadbolt are the two key figures behind the project.- Beta version and launch :...

. It is also used for knowledge management

Knowledge management

Knowledge management comprises a range of strategies and practices used in an organization to identify, create, represent, distribute, and enable adoption of insights and experiences...

 and business collaboration.

The standard release of Drupal, known as Drupal core, contains basic features common to content management systems. These include user account registration and maintenance, menu management, RSS

RSS

-Mathematics:* Root-sum-square, the square root of the sum of the squares of the elements of a data set* Residual sum of squares in statistics-Technology:* RSS , "Really Simple Syndication" or "Rich Site Summary", a family of web feed formats...

-feeds, page layout customization, and system administration.