MySQL is an open source relational database management system (RDBMS). Its name is a combination of the name "my" of the daughter of co-founder Michael widenius and the acronym "SQL" of structured query language. MySQL development project has provided its source code according to GNU General Public License Terms and various proprietary agreements. MySQL is owned and sponsored by a single for-profit company (MySQL AB, a Swedish company), which is now owned by Oracle Corporation. For proprietary use, there are several paid versions available with additional features.

MySQL is the core component of the lamp open source web application software stack (and other "amp" stacks). Lamp is the abbreviation of "Linux, Apache, mysql, Perl / PHP / Python". Applications using MySQL database include: Typo3, modx, Joomla, WordPress, simple machine forum, phpbb, MyBB and Drupal. MySQL is also used on a number of compelling large sites, including Google (though not search), Facebook, twitter, Flickr and Youtube.

MySQL is written in C and C + +. Its SQL parser is written in yacc, but it uses a self-made lexical analyzer. MySQL can run on many system platforms, including AIX, bsdi, FreeBSD, HP-UX, ecomstation, i5 / OS, IRIX, Linux, Mac OS, Microsoft Windows, NetBSD, Novell Netware, OpenBSD, OpenSolaris, OS / 2 warp, QNX, Oracle Solaris, Symbian, SunOS, SCO OpenServer, SCO UnixWare, SANOS and tru64. There is also a MySQL to OpenVMS port.

MySQL server software itself and client library are distributed under dual license. Starting June 28, 2000 (extended with the 2009 floss license exception), or using proprietary licenses, which will be available under GPL version 2.

Support can be obtained from official manuals. In addition, free support is available on different IRC channels and forums. Oracle offers paid support through its MySQL enterprise products. They differ in the scope and price of services. In addition, there are many third-party organizations to provide support and services, including MariaDB and percona.

MySQL received positive reviews, and the reviewers noticed that it "performed very well in general", and that "the developer interface is there, and the documentation (not to mention the feedback in the real world through websites, etc.) is good.". It has also been tested as a "fast, stable and true multi-user, multi-threaded SQL database server"