If you have root-level access to a hosting server, it indicates that you'll have full control of it. In other words, you can set up any server-side app whatever the changes that it will make to the software environment on your server, and you'll be able to both access and change any kind of file, including system files, and modify various settings. This can be done by connecting to the server as a root user that has full privileges to do all these things and also to generate other users, including users that also have full privileges. This connection can be established with a web-based graphical interface or a Secure Shell console. For safety reasons, it is recommended that you create another user for your everyday work and employ the root user only when you need to customize the server or to set up software that may be required by a script-driven application that you want to run.