A watch is a small portable clock which displays the current time. Until the advent of digital (quartz) watches, only purely mechanical timepieces were used. There are wrist watches and pocket watches. Watches may be collectible; they are often made of precious metals, and can be considered an article of jewelry.
Prominent makers of mechanical watches include:
Watch (timepiece)
A wristwatch.
The science of timekeeping, clocks and watches is horology.
Watch (period of duty)
Naval ships divide the day into four-hour watches, or on-duty periods. See ship's bells.
The term in general use can mean any period of duty or responsibility.