MariaDB is a community-developed, commercially supported fork of the MySQL relational database management system (RDBMS), intended to remain free and open-source software under the GNU General Public License. Development is led by some of the original developers of MySQL, who forked it due to concerns over its acquisition by Oracle Corporation in 2009. MariaDB is intended to maintain high compatibility with MySQL, with exact matching with MySQL APIs and commands, allowing it in many cases to function as drop-in replacement for MySQL. However, new features are diverging. It includes new storage engines like Aria, ColumnStore, and MyRocks. Its lead developer/CTO is Michael "Monty" Widenius, one of the founders of MySQL AB and the founder of Monty Program AB. On 16 January 2008, MySQL AB announced that it had agreed to be acquired by Sun Microsystems for approximately $1 billion. The acquisition completed on 26 February 2008. Sun was then bought the following year by Oracle Corporation. MariaDB is named after Widenius' younger daughter, Maria. (MySQL is named after his other daughter, My.) MariaDB version numbers follow MySQL's numbering scheme up to version 5.5. Thus, MariaDB 5.5 offers all of the MySQL 5.5 features. There exists a gap in MySQL versions between 5.1 and 5.5, while MariaDB issued 5.2 and 5.3 point releases. Since specific new features have been developed in MariaDB, the developers decided that a major version number change was necessary. The MariaDB Foundation mentions:MariaDB Server will remain Free and Open Source Software licensed under GPLv2, independent of any commercial entities. MariaDB's API and protocol are compatible with those used by MySQL, plus some features to support native non-blocking operations and progress reporting. This means that all connectors, libraries and applications which work with MySQL should also work on MariaDB—whether or not they support its native features. On this basis, Fedora developers replaced MySQL with MariaDB in Fedora 19, out of concerns that Oracle was making MySQL a more closed software project.