If you have root-level access to a server, this means that you will 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 setting on the server, and you can both access and update any file, which includes system files, and modify 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 generate other users, including users who also have full privileges. This connection can be established using a web-based graphical interface or a Secure Shell console. For safety reasons, it's recommended that you create a different user for your daily work and employ the root user only when you have to customize the server or to install software which may be required by a script-driven application that you want to run.