Having root-level access to your server signifies that you will be able to view and change any file on it, including crucial system files. You can also install software which can change specific settings on your server during the process, so the installation is possible only if you are signed in as the root user. The latter has full privileges, which means that you will have full control over the machine at any time and you'll be able to do anything you would like. You can also create additional users either with identical rights or with fewer rights, based on what you require them for - daily tasks, other server administrators, etcetera. 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 which can be done using other accounts. You can use a web-based graphical interface or a Secure Shell console to connect to the server and to manage it at the root level.