A pocket watch is a watch

Watch

A watch is a small timepiece, typically worn either on the wrist or attached on a chain and carried in a pocket, with wristwatches being the most common type of watch used today. They evolved in the 17th century from spring powered clocks, which appeared in the 15th century. The first watches were...

 that is made to be carried in a pocket, as opposed to a wristwatch

Watch

A watch is a small timepiece, typically worn either on the wrist or attached on a chain and carried in a pocket, with wristwatches being the most common type of watch used today. They evolved in the 17th century from spring powered clocks, which appeared in the 15th century. The first watches were...

, which is strapped to the wrist

Wrist

In human anatomy, the wrist is variously defined as 1) the carpus or carpal bones, the complex of eight bones forming the proximal skeletal segment of the hand;...

. They were the most common type of watch from their development in the 16th century until wristwatches became popular after World War I

World War I

World War I , which was predominantly called the World War or the Great War from its occurrence until 1939, and the First World War or World War I thereafter, was a major war centred in Europe that began on 28 July 1914 and lasted until 11 November 1918...

 during which a transitional design, trench watch

Trench watch

The Trench watch was a type of watch that came into use by the military during World War I, as pocket watches were not practical in combat. It was a transitional design between pocket watches and wrist watches, incorporating features of both....

es, were used by the military. Pocket watches generally have an attached chain

Chain

A chain is a sequence of connected links.Chain may also refer to:Chain may refer to:* Necklace - a jewelry which is worn around the neck* Mail , a type of armor made of interlocking chain links...

 to allow them to be secured to a waistcoat

Waistcoat

A waistcoat or vest is a sleeveless upper-body garment worn over a dress shirt and necktie and below a coat as a part of most men's formal wear, and as the third piece of the three-piece male business suit.-Characteristics and use:...

, lapel, or belt loop

Belt (clothing)

A belt is a flexible band or strap, typically made of leather or heavy cloth, and worn around the waist. A belt supports trousers or other articles of clothing.-History:...

, and to prevent them from being dropped.