If you have root-level access to a hosting server, this means that you'll have full control over it. In other words, you can set up any server-side app regardless of the changes that it will make to the software environment on your server, and you can both access and modify any kind of file, including system files, and change various settings. This can be done by connecting to the server as a root user that has full privileges to perform the aforementioned things and also to create other users, including users who also have full privileges. The connection can be established with a web-based graphical interface or a Secure Shell console. For security reasons, it's recommended that you create one more user for your daily work and use the root user only when you have to modify the server or to set up software which may be required by a script-driven application that you wish to run.