A (non-ink) pen used as an input device on either a graphics-tablet or touch-screen.
From Wikipedia:
A stylus is a writing utensil, or a small tool for some other form of marking or shaping, for example in pottery. It can also be a computer accessory that is used to assist in navigating or providing more precision when using touchscreens. It usually refers to a narrow elongated staff, similar to a modern ballpoint pen. Many styli are heavily curved to be held more easily. Another widely-used writing tool is the stylus used by blind users in conjunction with the slate for punching out the dots in Braille.
