They are called automatic because the wearer does not need to wind the watch to generate power, the watch winds itself automatically once a person put it on the wrist. The arm motion causes the rotor, a metal weight attached to a winding mechanism, to rotate back and forth in a circular motion to wind the mainspring, a flat coiled spring that powers mechanical watches.
This watches are powered by a battery. They need little maintenance, just a change of battery every year or so.
Some quartz watches get their electricity from a mini electrical generator incorporated into the watch movement, powered by the wearer’s wrist, which causes a rotor to spin rapidly. These watches are sold by Japanese or Swiss companies under the name of “Kinetic”, “Autoquartz”or “Omegamatic .
Other quartz watches get their electricity from light which is transformed into electrical power by a solar cell located under the dial. This watch can be found under the name of “Eco-Drive”.
MANUAL WIND WATCHES:
Collectors find these kind of watches desirable, even though they are manual wind watches, which means that the wearer has to wind it every one or two days by the crown in order to run. They are still produced in Switzerland and can even cost over $5,000.
Some unique models can reserve up to 8 days of power and will usually have power-reserve indicator on the dial.