Watches are typically classified according to how they're powered. There are two main types that work in several different ways and can be found in jewelry stores today.
The quartz watch is the most popular type, due to its extreme accuracy, limited maintenance needs and affordability.
These watches are powered by a battery which causes the quartz crystal inside to vibrate at a certain rate per second. These vibrations are counted by a computer chip inside the watch and transmitted to either the LCD display or the motor of an analog watch to display the time.
First introduced by Seiko, the kinetic watch uses an alternate power source: the motion of the wearer. Rather than running on a battery, the movement of the wearer's arm generates the energy needed to vibrate the quartz crystal. A capacitor inside the watch "charges" during wear and will keep the watch on time for at least 14 days, even if it has not been worn.
Instead of movement charging the capacitor, exposure to a light source performs this task. Typically, the wearer can go about 72 hours before having to expose the watch to light again.
The oldest type of watch, mechanical watches are still intricately crafted around the world. Full of moving parts, the mechanical watch typically requires yearly maintenance.
No batteries or quartz crystals are found within a mechanical watch. By winding up the internal mechanism, the watch is powered. It must be wound every few days to ensure it keeps runnning.
Automatic mechanical watches can still be wound up, but they can also be powered by movement. Similar to kinetic quartz watches, an automatic utilizes a weight inside that spins around as the watch is worn, winding up the mechanism. If the watch is worn regularly, it will wind itself and maintain acurrate time.