Having root-level access to a server means that you'll be able to view and change any file on it, which includes important system files. You can also set up software that can change specific settings on your server during the process, so the installation is possible only if you are logged in as the root user. The latter 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 can also make various other users either with identical rights or with fewer rights, based on what you require them for - day-to-day tasks, other server admins, etc. 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 can be done via other accounts. You may use a web-based graphical interface or a Secure Shell console to connect with the server and to control it at the root level.