If you have root-level access to a server, this means that you will have full control over it. That is to say, you can install any server-side application whatever the changes that it will make to the software setting on the server, and you are able to both access and modify any file, including system files, and modify any settings. This can be done by connecting to the server as a root user who has full privileges to perform the aforementioned things and also to create 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 security reasons, it is recommended that you make another user for your daily work and employ the root user only when you need to customize the server or to set up software that may be needed by a script-driven app that you'd like to run.