Watch
A wristwatch.
A watch is a small portable clock which displays the current time and sometimes the current day, date, month and year. In modern times they are usually worn on the wrist, although prior to the 20th century most were pocket watches, which had covers and were carried separately, often in a pocket, and hooked to a watch chain.
Current watches are often digital watches, powered by a battery that causes a small crystal, usually quartz, to vibrate. The watch keeps time by "counting" these vibrations.
In earlier times mechanical timepieces were used, powered by a spring wound regularly by the user. The invention of kinetic watches allowed for a "perpetual" winding without special action from the wearer: it works by an irregular weight that rotates to the movement of the wearer's body, automatically winding the watch.
Watches may be collectible; they are often made of precious metals, and can be considered an article of jewelry.
Prominent makers of watches include:
The science of timekeeping, clocks and watches is horology.
In naval parlance, the day is divided 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.