Why would I want a virtual private server instead of using shared hosting?
There are limitations to having shared hosting services and the biggest one is you cannot usually compile or install your own software. More specifically say you want your web server to be able to use a certainly technology like PHP but the host does not have it setup for you. As a regular user you cannot install the software needed to use PHP but in the Virtual Private Server system you can install any software you want because you have full control. This means that you would be able to install PHP and any other software you want.