MySQL (ronunciation href="http://en.wikipedia.org/wiki/Helpronunciation">pronounced /maɪˌɛskjuːˈɛl/ "my S-Q-L" or sometimes "my sequel") is a multithreaded, multi-user SQL database management system (DBMS) which has more than 11 million installations. The basic program runs as a server providing multi-user access to a number of databases.

It was originally financed in a similar fashion to the JBoss model, MySQL was owned and sponsored by a single for-profit firm, the Swedish company MySQL AB, now a subsidiary of Sun Microsystems, which holds the copyright to most of the codebase. The project's source code is available under terms of the GNU General Public License, as well as under a variety of proprietary agreements.