phpMyAdmin is a tool written in PHP that allows you to administrate your MySQL databases. You can execute SQL statements, work with fields (add, edit, delete), work with tables (create, alter, drop), create additional databases, and much more. phpMyAdmin is intended for advanced users. Most PHP scripts will automatically setup the database for you, so you probably won't need to use phpMyAdmin..
phpMyAdmin can be accessed at http://www.yourdomain.com/phpMyAdmin. Please visit http://www.phpmyadmin.net for more information on using phpMyAdmin.