Minimize, Restore, Close

These three buttons do what they say.

The underline ( _ ) "squashes" the window (minimize).
The center picture is a window and when pressed it becomes full-size.
The right picture is an X and it means "the end". When pressed it closes a window.

When the underline is pressed the squashed (minimized) window doesn't close.
It is named in the task bar and its button sticks up a little (ready to be clicked).

My Documents is open. My Computer is minimized.