The OS provides a user interface (UI), an environment for the user to interact with the machine. The UI is either graphical or text-based.
The OS on most computers and smartphones provides an environment with tiles, icons and/or menus. This type of interface is called the graphical user interface (GUI) because the user interacts with images through a mouse, keyboard or touchscreen.
An OS also provides a method of interaction that is non-graphical, called the command line interface (CLI). This is a text-only service with feedback from the OS appearing in text. Using a CLI requires knowledge of the commands available on a particular machine.
Advantages of using the command line include:
Some games, such as Minecraft, also make use of a command line tool which allows the user to bypass the main interface and alter the game’s mechanics or environment.