Mouse
Mouse is the input device that generates messages about cursor movement, button clicks and wheel rotation.
Position of the mouse cursor is in units that corresponds with the current screen mode, resolution and other parameters. E.g. if the screen is in text mode, mouse position will be expressed in characters. If it is in graph mode, position will be in pixels.
Position can be out of the screen resolution range - also greater or equal than screen width and height, as well as negative.