An automatic (skeleton) or self-winding watch is a mechanical watch in which there is no quartz battery but instead a mainspring that is wound automatically as a result of the natural motion of the wearer. This provides enough energy to power the watch.
The watch will need to be worn for more than 8 hours/day to ensure it works continuously. If it hasn't been worn for a long time the watch may stop. In order to avoid this the wearer may manually wind the watch by winding the crown (while its pushed in) approx. 20 to 30 laps until the spring within the watch is dense.