What is the difference between mechanical and quartz watches?

A mechanical watch is powered by a tightly coiled mainspring. Manual mechanical watches must be hand wound to keep them in power, typically every other day. An automatic watch is also mechanical; however, it is predominantly wound by a rotor weight that turns with the wearer's movements. A quartz watch, however, is battery powered and extremely accurate. On average, a battery in a basic time-and-date quartz watch can last anywhere between one and five years.