MySQL and MariaDB

The most widely used open source database for Web apps (and many other things) remains MySQL. Support for multiple storage engines, clustering, full-text indexing, and plenty of other professional features have allowed numerous other apps profiled here, from WordPress to Movable Type, to rely on MySQL as their default database. Graphical front ends, such as phpMyAdmin and Adminer, make using the database far less of a chore. And for those seeking escape from the long shadow of Oracle, there's a community fork named MariaDB, maintained by MySQL's original lead developer, Monty Widenius.