When you have root-level access to a server, it indicates that you'll have full control over it. In other words, you can install any server-side application no matter what the changes that it'll make to the software environment on your server, and you can both access and update any file, including system files, and change any settings. This can be done by connecting to the server as a root user which has full privileges to do the aforementioned things as well as to make 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 create one more user for your daily work and employ the root user only when you need to customize the server or to set up software which may be needed by some script-driven app that you wish to run.