Having root-level access to a server means that you will be able to view and update any file on it, including crucial system files. You may also set up software that can update certain settings on your server throughout the, so the installation can be done only if you're logged in as the root user. The latter has full privileges, i.e. you will have full control over the machine at any time and you can perform anything you would like. You may also generate additional users either with identical rights or with fewer rights, based on what you require them for - day-to-day tasks, other server admins, etcetera. To be on the safe side, it's usually recommended to employ the root account only when you actually need it and not for tasks that you can do through other accounts. You may use a web-based graphical interface or a Secure Shell console to connect with the server and to manage it at the root level.