A shell is a program that interprets input and such -- the interactive Bash shell is the same program that interprets scripts written for it. You can remotely

A shell is a program that interprets input and such -- the interactive Bash shell is the same program that interprets scripts written for it. You can remotely call shells and interact with them without showing anything to one's terminal. A terminal emulator connects your keyboard, mouse, and eyeballs to inputs/outputs of the shell. Those are terrible explanations, I'm sorry.