A touch-sensitive lamp is one that is activated by human touch rather than a flip, push button, or other mechanical switch. These lamps are popular as desk and nightstand lamps. They act on the principle of body capacitance. Touch- lamp switches may be dimmable, allowing the brightness of the lamp to be adjusted by multiple touches. Most stop at level 3, which is for the brightest use, while some at ONE only as ON/OFF switch.