When you use a script-driven application for your site, any information which both you and the website users create will be stored inside a database - a collection of data, that's organized in cells and tables for simplier and easier reading and writing. The latter is carried out by using special software referred to as database management system and one of the most popular ones world-wide is MySQL. A lot of script applications are designed to work with MySQL since it is easy to work with, it performs very well on a hosting server and it's also universal as it can work with widely used web programming languages (Java, PHP, Perl, Python) and on a number of hosting server OS (Windows, Linux, UNIX). There are thousands of scripts which use MySQL, including extremely popular ones like Moodle, Joomla and WordPress.