MySQL (/maɪ ˌɛs kjuː ˈɛl/ "My S-Q-L",^[6] officially, but also called /maɪ ˈsiːk wəl/ "My Sequel") is (as of July 2013) the world's second most^[a] widely used relational database management system (RDBMS)^[9] and most widely used open-source RDBMS.^[10] It is named after co-founder Michael Widenius's daughter, My.^[11] The SQL acronym stands forStructured Query Language.

The MySQL development project has made its source code available under the terms of the GNU General Public License, as well as under a variety of proprietary agreements. MySQL was owned and sponsored by a single for-profitfirm, the Swedish company MySQL AB, now owned by Oracle Corporation.^[12]

MySQL is a popular choice of database for use in web applications, and is a central component of the widely usedLAMP open source web application software stack (and other 'AMP' stacks). LAMP is an acronym for "Linux, Apache, MySQL, Perl/PHP/Python." Free-software-open source projects that require a full-featured database management system often use MySQL.

For proprietary use, several paid editions are available, and offer additional functionality. Applications which use MySQL databases include: TYPO3, MODx, Joomla, WordPress, phpBB, MyBB, Drupal and other software. MySQL is also used in many high-profile, large-scale websites, including Google^[13][14] (though not for searches),Facebook,^[15][16][17] Twitter,^[18] Flickr,^[19] and YouTube.^[20]