Terminal, shell, command line: same room, different words

You'll hear three words used for this thing, sometimes in the same sentence. Here's what each one means, so the words stop tripping you up.

• Terminal. The window. The actual app with the text box in it. On a Mac it's an app literally called Terminal. Think of it as the screen and keyboard.
• Shell. The program running inside that window. It's the part that reads what you typed, figures out what you meant, runs it, and prints the result. Common shells are called bash and zsh. You do not need to care which one you have. They all work the same for everything in this course.
• Command line. The thing you type. One line of text, which is a command. "Command line" is just a description of the typing surface.

If that's a lot of words for one box, here's the shortcut: people use all three to mean "the place where you type commands." When this course says terminal, shell, or command line, it means the same room. You will not be quizzed on the difference. It's here so the words don't make you feel behind.

How it compares to clicking

Everything you do with a mouse has a typed version.

With the mouse	In the terminal
Open a folder by double-clicking it	cd (change directory)
Look at what's inside a folder	ls (list)
Make a new folder	mkdir (make directory)
Make a new empty file	touch

Same files. Same computer. The terminal isn't a separate secret machine. It's a different door into the one you already own. When you make a folder by typing mkdir, you can switch to your normal file window and watch the folder sitting right there. It's all one place.