MySQL is dual-licensed under both the GNU General Public License (GPL) and a commercial license. This means that you can choose to use MySQL under the terms of the GPL for free, as long as you comply with the terms of the license. Alternatively, you can purchase a commercial license from Oracle, the current owner of MySQL, which allows you to use MySQL without the restrictions of the GPL. This is useful for organizations that do not want to release their own code under the GPL or have other concerns about using open source software.