Getting started with MySQL
You can use MySQL to create databases that contain several tables of information, and within each table you can hold several fields of information. Once you have an existing database you can always add more tables, or remove tables at any time.
MySQL with PHP
As powerful as MySQL is on its own, it is even more powerful when coupled with PHP. PHP allows you to interact with your MySQL database directly from your website. This can be used for something as simple as keeping a list of email addresses, to something more extensive like a forum or a database of customers, their shopping carts, and their previous purchases.