Having root-level access to your server means that you can view and update any file on it, including important system files. You can also install software which can update particular settings on your server throughout the, so the installation is possible only if you are logged in as the root user. The latter has full privileges, i.e. you will have full control over your machine at any time and you can perform anything you want. You may also generate additional users either with the same rights or with fewer rights, depending on what you require them for - everyday tasks, other server admins, etc. To be on the safe side, it is generally recommended to use the root account only when you really need it and not for tasks that can be done through other accounts. You can use a web-based graphical interface or a Secure Shell console to connect with the server and to control it at the root level.