MariaDB is a community developed branch of the MySQL database that uses the Maria engine by default.
We can't use the MySQL name as this is trademarked by Sun, and Sun has chosen to keep that trademark quite exclusive to itself. The name MySQL (just like the MyISAM storage engine) comes from Monty's first daughter "My". MariaDB continues this tradition by being named after his younger daughter.
To provide a community developed, stable, and always Free branch of MySQL that is, on the user level, compatible with the main version. We strive for total interoperability with our upstreams and our own community.
MariaDB will be kept up to date with the latest MySQL release from the same branch. For example MariaDB 5.1 will be kept up to date with MySQL 5.1.
We will do a merge from the MySQL branch for every new MySQL release or when there is some fatal bugfix applied to the main branch.
We strive to keep our main trees as free from bugs as possible. It should be reasonably safe to pull from our trees at any time. We work to provide builds of the main branch and active development branches every month.
MariaDB is available under the terms of the GPL v2 license, just like MySQL.
The MariaDB project is the brainchild of Michael "Monty" Widenius, the founder of MySQL and Monty Program Ab.