All script applications including forums or virtual stores save their information inside a database - a set of cells and tables containing all the Internet site data like items, prices, comments, and so on. Every time you open a certain page, the script connects to the database and retrieves the needed data, then shows it. The mid-level software which connects the script and the database is called a database management system and amongst the most well-known ones is MySQL. The latter is widely used as it can run on a variety of platforms (Linux, Windows, UNIX) and with a number of scripting languages (PHP, Perl, Python, Java), not mentioning its amazing performance even with huge databases. Lots of famous platforms such as Joomla or WordPress work with MySQL databases to save their content.