When you have root-level access to a server, it indicates that you'll have full control of it. That is to say, you can install any server-side application no matter what the changes that it will make to the software setting on your server, and you can both access and change any file, which includes system files, and change any settings. You can do this by connecting to the server as a root user who has full privileges to perform all these things and also to create other users, including users that also have full privileges. This particular can be established with a web-based graphical interface or a Secure Shell console. For safety reasons, it is recommended that you make another user for your everyday work and employ the root user only when you need to customize the server or to install software which may be needed by a script-driven app that you'd like to run.