When you have root-level access to a hosting server, this means that you'll have full control over it. That is to say, you'll be able set up any server-side application regardless of the changes that it will make to the software setting on your server, and you will be able to both access and update any file, including system files, and change any settings. You can do this by connecting to the server as a root user which has full privileges to do the aforementioned things and to generate other users, which includes users that also have full privileges. The connection can be established through a web-based graphical interface or a Secure Shell console. For safety reasons, it's recommended that you create one more user for your daily work and use the root user only when you have to customize the server or to set up software that may be required by a script-driven app that you would like to run.