Having root-level access to a server signifies that you can view and modify any file on it, including crucial system files. You may also install software that can change certain settings on your server throughout the, so that the installation can be done only if you are signed in as the root user. The aforementioned has full privileges, which means that you will have full control over the machine whenever you want and you can perform anything you would like. You may also make additional users either with identical rights or with fewer rights, based on what you want them for - day-to-day tasks, other server admins, etc. To be on the safe side, it is generally recommended to use the root account only when you actually need it and not for tasks that you can do through other accounts. You can use a web-based graphical interface or a Secure Shell console in order to connect with the server and to manage it at the root level.