A mechanical watch movement has about 130 parts. The intricate assembly transfers motion to the hands at a steady pace.
A mechanical watch is powered by a coiled spring. When you wind the watch, this spring tightens, storing energy; when the watch is keeping time, the tension on the spring is slowly released, and the stored energy is used to keep the watch going.
Precisely measured gears then transfer this energy to the hour hand. A mechanism called an escapement ensures that the minute hand takes an hour to go around the dial. Gears turn the hour hand twice a day, and the second hand once a minute.
To keep your watch running smoothly, most models should be professionally serviced every two or three years; consult the manufacturer or vendor for your specific needs.