But what is an automatic watch and how does it really work?

Men’s automatic watches are also referred to as self-winding watches. They are perfunctory watches, whose primary spring is wound impulsively by the native action of the man’s arm, so that there is no need to manually wind the timepiece.

The watch has a semicircular rotor that turns on a pivot within the watch case. The usual movements of the man’s arm and wrist cause the rotor to pivot back-and-forth on its staff, which is attached to a winding mechanism. The motion of the man’s arm is converted into the circular stirring of the rotor that, through a series of gears, eventually winds the primary spring. Modern self-winding mechanisms have two ratchets and wind the mainspring during both clockwise and counter clockwise rotor motions.

The fully-wound primary spring in an average timepiece can store enough energy for about two days, allowing automatic watches to keep running through the night while off the wrist. Commonly, automatics can also be wound manually by turning the crown, so that the timepiece will continue running even when not worn, or when the man’s wrist movements are not enough to wound it automatically.

Today, electronic quartz watches that are controlled by arm motion have been developed. A rotor turns a small electrical generator, charging a rechargeable battery or capacitor which powers the quartz motion. This automatic quartz disposition gives the precision of quartz without the need to replace the battery or capacitor for decades.