phpMyAdmin is a feature-rich tool coded in PHP, that will give you total control over a MySQL database. You may do virtually anything - set up fields, rows and tables, remove them or alter their data, export or import a whole database or just a specific part of it, and execute MySQL commands. The tool is necessary when you want to switch hosting companies, simply because you could conveniently create a full backup of a database in several formats (SQL, CSV, XML). You'll end up with one file that contains the whole content of the database, so you can easily download it from the present provider, upload it to the web server of the new one and import it through the same tool on their end. Your site will look exactly the same, simply because all script applications store their data inside a database. With phpMyAdmin you may also effortlessly search and replace information of your choice across the entire website - a word, a phrase or a link, for instance.