Having full root-level access signifies that you can access and customize every file on a particular server, which includes all system files, and to change system settings or install server-side software which may be required by specific scripts and even offline applications to function properly. A server is accessed at the root level through a root user, which has full privileges to perform any of the abovementioned things. The root user may also generate various other users. For security reasons, you're advised to have a separate account for daily tasks and to use the root account only if you actually need to perform some task on the website hosting server. The root-level access function will provide you with full control of your server from almost any location, given that you know the user credentials.