When you have root-level access to a hosting server, it means that you will have full control of it. In other words, you can set up any server-side app regardless of 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 modify any settings. You can do this by connecting to the server as a root user who has full privileges to perform all these things as well as to make other users, which includes users who also have full privileges. This connection can be established using a web-based graphical interface or a Secure Shell console. For safety reasons, it's recommended that you create a different user for your daily work and use the root user only when you need to customize the server or to install software which may be needed by some script-driven application that you wish to run.