All script applications including forums or online shops keep their info inside a database - a set of cells and tables that contains the Internet site information including items, prices, comments, etc. Every time you open a particular page, the script connects to the database and retrieves the specified data, then shows it. The mid-level software which connects the script and the database is called a database management system and one of the most famous ones is MySQL. The latter is frequently used as it operates on different platforms (Windows, Linux, UNIX) and with a variety of scripting languages (Python, PHP, Perl, Java), not mentioning its great functionality even with massive databases. Numerous widely used platforms like WordPress or Joomla use MySQL databases to store their content.