Every watch of the house runs on a quartz movement. Its timekeeping comes from a tiny piece of quartz crystal, cut in the shape of a tuning fork.
The crystal
Quartz has a useful property: put a small electric current through it and it vibrates at a very steady rate. The crystal in a watch is cut to vibrate 32,768 times a second.
The count
A circuit counts those vibrations. Each time it reaches 32,768, a second has passed, and it sends a pulse to a small stepping motor. The motor turns the gears, and the gears turn the hands.
What it means on the wrist
Because the crystal keeps the rate, the watch keeps time whether it is worn, left on a table or put away in a drawer. There is nothing to wind. Its only need is a fresh battery every few years.
Changing the battery
When the watch begins to lose time, or stops, the battery is due. Have it changed promptly: a spent cell left inside can leak. Ask for the case seals to be checked at the same time, so the water resistance stays as it left the house.