A watch is a small portable clock that displays the current time and sometimes the current day, date, month and year. In modern times they are usually worn on the wrist, although before 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 "Automatic" or "Self-Winding" watches allowed for a constant 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 jewelery.

From the wikipedia - Used with permission