When you have root-level access to a server, this means that you'll have full control of it. That is to say, you can install any server-side app no matter what the changes that it'll make to the software environment on your server, and you'll be able to 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 that has full privileges to perform all these things as well as to generate other users, which includes users who also have full privileges. The connection can be established through a web-based graphical interface or a Secure Shell console. For safety reasons, it is recommended that you create a separate user for your daily work and use the root user only when you have to modify the server or to install software that may be needed by some script-driven app that you want to run.