MySQL is (as of July 2013) the world's second most widely used relational database management system and most widely used open-source RDBMS.
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-profit firm, the Swedish company MySQL AB, now owned by Oracle Corporation.
MySQL is a popular choice of database for use in web applications, and is a central component of the widely used LAMP open source web application software stack ("Linux, Apache, MySQL, Perl/PHP/Python.") Free-software-open source projects that require a full-featured database management system often use MySQL.