What's the difference between quartz and mechanical/automatic movements?

The intricate movements on the inside of a watch are the elements that comprise the main timekeeping mechanism. Most wristwatches feature either quartz or mechanical automatic movement inside.

A mechanical watch is driven by a mainspring mechanism inside, which has to be wound periodically and features a series of gear mechanisms. Automatic mechanical watches primarily rely on the movement of the wrist. You do not have to shake the timepiece to keep it running since the normal everyday moment on your wrist charges the winding reserve. When the watch is removed, the movement will 'wind down” in anywhere from 10 to 72 hours, depending on the capacity size of the power reserve. A watch winder is recommended if you do not plan to wear this watch for any duration after the power reserve winds down.

A quartz watch is powered by the battery inside and keeps running when removed from the wrist. The watch features an ultra-thin sliver of quartz crystal that is activated by the battery and predictably vibrates at an extremely high-frequency, which provides accurate timekeeping movement. The battery in a quartz watch has to periodically be replaced every 1.5 to 2 years.