When you have root-level access to a server, it means that you'll have full control over it. In other words, you'll be able set up any server-side app whatever the changes that it will make to the software environment on your server, and you are able to both access and modify any file, which includes system files, and modify various settings. You can do this by connecting to the server as a root user which has full privileges to perform the aforementioned things and to make other users, including users who also have full privileges. The connection can be established through a web-based graphical interface or a Secure Shell console. For safety reasons, it is recommended that you make a different user for your everyday work and employ the root user only when you have to customize the server or to install software that may be required by a script-driven application that you would like to run.