If you are planing on host numerous websites, you will need to become accustomed with the following software to help manage your Virtual Private Server.
cPanel
The cPanel is a companion piece to WHM and allows you or your client to manage one user account on the server set up email accounts, add sub-domains, view website statistics, and most other tasks related to a specific user through an interface.
Plesk
Parallels Plesk is control panel software that lives on your server. The browser-based, graphical interface allows you to create system user accounts, assign domains to those users, create hosting packages, monitor user activity, set up email accounts, add sub-domains, view website traffic statistics, and most other administrative tasks.
WHM
WHM (Web Host Manager) is a companion piece to cPanel and allows you to manage your server at the super-user level so that you can create system user accounts, assign domains to those users, create hosting packages, and monitor user activity.
