PHP MySQL is a popular open source database management system that is commonly used in PHP-based web applications.
What is MySql?
MySQL is a database system used on the web. Basically, a MySQL database allows you to create a relational database structure on a web-server somewhere in order to store data or automate procedures.
If you think of it in comparison to Microsoft Access, MySQL is what holds all of your data in database objects called tables.
PHP acts as your queries (among other things), and your forms are basically web pages with fields in them. With all of this combined, you can create truly spectacular projects on the web.