If you have root-level access to a hosting server, it means that you will have full control of it. That is to say, you can set up any server-side app no matter what the changes that it will make to the software setting on the server, and you're able to both access and modify any file, which includes system files, and change various settings. This can be done by connecting to the server as a root user who has full privileges to do all these things as well as to make other users, which includes users that also have full privileges. This connection can be established through a web-based graphical interface or a Secure Shell console. For security reasons, it is recommended that you create a different user for your everyday work and use the root user only when you need to modify the server or to set up software that may be needed by some script-driven application that you want to run.