MySQL databases
A database can be described as an integrated collection of logically related records or files consolidated into a common pool that provides data for one or more multiple uses.
A database is the core to large websites that offeer functionality and also interaction with a user. A whole website could store all of its content in a database with very little code required to display these pages.
So why MySQL databases ?
MySQL is the world's most popular open source database.
MySQL is often used in free software projects that require a full-featured database management system, such as WordPress and phpBB.