The following are descriptions of the three movement types:
Quartz Watches
Watches that have quartz movements are a relatively new development in watch history. Quartz crystals have a unique property in that when they are compressed or bent, they conduct a constant voltage, or pulse, on their surface. This constant voltage can be used to power quartz watches with exact precision. Rather than a wound spring (mechanical movement), quartz watches rely on a battery for their energy. The battery sends electrical energy to the tiny quartz crystal, which in turn creates a pulse at regular, constant levels. Because the pulse (also called an impulse) is extremely constant, quartz movements ensure precision timekeeping, accurate down to hundredths of a second. To convert the impulse into a steady power that can move the watch hands at regular intervals, the impulse is simply passed through a stepping motor that converts the electrical energy of the impulse into mechanical energy that is needed to run the watch. Since the early 1970's, quartz watches have become very popular, for both manufacturer and consumers, due to the fact that quartz watches are less expensive than mechanical movement watches and can be easily manufactured in large volumes.
Mechanical Movements
If a watch is said to have mechanical movement, this means that the watch has a device for keeping time, which uses the energy from a wound spring, and keeps time through the highly regulated release of that energy through a set of gears and an escapement. This device must be wound periodically, ensuring that the wound spring is continually loaded to power the watch. It differs from the typical quartz watch in that it uses purely mechanical components to keep time. A normal mechanical watch can run for about 40 hours on one full winding of the mainspring, and a few designs that can last up to 8 or 10 days are also available. The general design of mechanical movement watches have not changed notably in the past fifty years. But, the development of greater technology and modern materials has changed the way mechanical movement watches are manufactured.
Automatic Movements
Watches that are powered by automatic movements operate similar to a watch with mechanical movements, except that the winding of the spring occurs automatically, every time the wearer moves his or her arm. A rotor that turns in response to motion winds the watch's mainspring, supplying the needed energy to power the watch. The obvious benefit of an automatic movement is that there is never a need to replace a battery or to wind the watch. Keeping this in mind, it is necessary to occasionally "tune up" an automatic watch to ensure timekeeping is precise.