CLI

CLI is your command-line interface. This is typically a black background with white text. The two other interfaces you can typically find are ncurses which like a CLI is found in a terminal, as well as GUI which is what most of use now such as an X server or Microsoft Windows. You will usually use a mouse in a GUI where you will only be able to use a mouse for cut and paste in a CLI.

If you're using a UBO CLI and want to try cut and paste with a mouse, check out the official gpm website.