A chronograph is a timepiece or watch with both timekeeping and stopwatch functions. Digital chronographs use a digital display for both timekeeping and stopwatch functions, either with separate displays or by switching modes on a single display. Analog-digital chronographs have a standard analog watch with permanent center seconds and a separate digital display that usually operates independently of the analog section. A fallback will reset to zero and then continue to run when the reset button is pushed while the stopwatch is running. In contrast, most mechanical chronographs will reset to fifty only when the stopwatch is stopped.