MariaDB is a database server that offers drop-in replacement functionality
for MySQL. MariaDB is built by some of the original authors of MySQL, with
assistance from the broader community of Free and open source software
developers. In addition to the core functionality of MySQL, MariaDB offers
a rich set of feature enhancements including alternate storage engines,
server optimizations, and patches.

MariaDB is primarily driven by developers at Monty Program, a company
founded by Michael "Monty" Widenius, the original author of MySQL, but
this is not the whole story about MariaDB. On the "About MariaDB" page you
will find more information about all participants in the MariaDB community,
including storage engines XtraDB and PBXT.
