Various extra features, called "complications", such as moon-phase displays and the different types of tourbillon, are sometimes included.
Some watches use radio clock technology to regularly correct the time.
Developments in the 2010s include smartwatches, which are elaborate computer-like electronic devices designed to be worn on a wrist.
Watches progressed in the 17th century from spring-powered clocks, which appeared as early as the 14th century.
During most of its history the watch was a mechanical device, driven by clockwork, powered by winding a mainspring, and keeping time with an oscillating balance wheel.
The concept of the wristwatch goes back to the production of the very earliest watches in the 16th century.