MediaWiki is a wiki software (a so-called wiki engine) originally developed for the free encyclopedia Wikipedia. Nowadays it is also used for various other projects of the non-profit Wikimedia Foundation. Since it is freely available to everyone, you can also find it for a variety of other projects on the Internet or in intranets.
The software is licensed under the GNU General Public License and written in the PHP5 programming language. MediaWiki uses the relational database MySQL or MariaDB to store the content.