MediaWiki is a free software wiki engine, licensed under the GNU General Public License, or GPL. The software was originally created to power Wikipedia, and, as it is free software, is now used to power many other sites of varying size, including CreationWiki, Conservapedia, the various projects of the Wikimedia Foundation, and Jimmy Wales's for-profit company, Wikia, as well as being applied in small wikis for a single group. A notably different use of the MediaWiki software is by the company Novell, which uses it to power several of its high-traffic websites, which are only editable by a select group, not the general public. As Wikipedia is an extremely high-traffic website, MediaWiki is highly optimized for performance.
The MediaWiki codebase is primarily written in PHP, and can utilize either the MySQL or PostgreSQL relational database systems. MediaWiki is free software, licensed under the GNU General Public License, or GPL. Several hundred optional extensions have been created for MediaWiki. A few extensions, such as ParserFunctions and Cite, are almost ubiquitously used throughout the wikisphere on MediaWiki installations. FlaggedRevs is one extension that has the potential to greatly limit the potential for readers to be exposed to the results of wiki vandalism.
Namespaces in MediaWiki
MediaWiki divides pages into logical subdivisions by means of namespaces, which, in MediaWiki, are denoted by a text string, descriptive of the purpose of the page, followed by a colon, all of which precedes the title. This yields titles in the form of Namespace:Title. MediaWiki is by default configured with certain stock namespaces, and others can easily be added for a website by those with access to the code. Different properties apply to different namespaces. The only exception to the naming scheme is that of the main namespace, which has no prefix.
Like many wikis, MediaWiki has a semi-WYSIWYG (an acronym for What You See Is What You Get) language for the editing of the content on the sites it powers, allowing users who do not know HTML to relatively easily generate web content of high technological quality.
Many interface elements, collectively known as system messages, are defined by pages in the MediaWiki namespace. These pages are, by default, protected to be only editable by administrators, as they define global interface elements.
MediaWiki allows articles to be broken up into sections for the sake of convenience, and generally allows these sections to be individually editable.