MySQL is just one database management system based around Structured Query Language. What this means is that you can create, administer and access database tables by sending text commands to a database server. This can be done using a terminal but PHP is very happy to do the job for you so that you can set up easy-to-use Web pages for the job.
The aim of these pages is to teach you how PHP can be used with MySQL to allow data to be stored and accessed. The concepts are fairly simple but the possibilities are amazing.
These pages assume you know the basics of HTML, CSS and PHP so if you do not you should go to those tutorials first. The terms and concepts which you need to understand are summarised in the background to databases section and you should look at those before starting here.
Hover over the links for a brief description.