MySQL

MySQL is a multithreaded, multi-user, SQL (Structured Query Language) Database Management System (DBMS) with an estimated six million installations. MySQL AB makes MySQL available as free software under the GNU General Public License (GPL), but they also dual-license it under traditional proprietary licensing arrangements for cases where the intended use is incompatible with the GPL.

Unlike projects such as Apache, where the software is developed by a public community, and the copyright to the codebase is owned by its individual authors, MySQL is owned and sponsored by a single for-profit firm, the Swedish company MySQL AB, which holds the copyright to most of the codebase. The company develops and maintains the system, selling support and service contracts, as well as proprietary-licensed copies of MySQL, and employing people all over the world who collaborate via the Internet. Two Swedes and a Finn founded MySQL AB: David Axmark, Allan Larsson, and Michael "Monty" Widenius.