A carrier pigeon is a homing pigeon

Homing pigeon

The homing pigeon is a variety of domestic pigeon derived from the Rock Pigeon selectively bred to find its way home over extremely long distances. The wild rock pigeon has an innate homing ability, meaning that it will generally return to its own nest and its own mate...

 (specifically a domesticated rock pigeon

Rock Pigeon

The Rock Dove or Rock Pigeon, is a member of the bird family Columbidae . In common usage, this bird is often simply referred to as the "pigeon"....

, Columba livia) that is used to carry messages. Using pigeons to carry messages is generally called "pigeon post

Pigeon post

Pigeon post is the use of homing pigeons to carry messages. Pigeons were effective as messengers due to their natural homing abilities. The pigeons were transported to a destination in cages, where they would be attached with messages, then naturally the pigeon would fly back to its home where the...

". Most homing or racing type varieties are used to carry messages. There is no specific breed

Breed

A breed is a group of domestic animals or plants with a homogeneous appearance, behavior, and other characteristics that distinguish it from other animals or plants of the same species. Despite the centrality of the idea of "breeds" to animal husbandry, there is no scientifically accepted...

 actually called "carrier pigeon". Carrier pigeons that are the basic Racing Homer

Racing Homer

A Racing Homer is a breed of pigeon that has been selectively bred for more speed, and enhanced homing instinct for the sport of Pigeon racing. A popular domestic pigeon breed, the Racing Homer is also one of the newest.-Development:...

 were used to carry messages in 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...

 and World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

. Thirty-two pigeons were presented with the Dickin Medal

Dickin Medal

The Dickin Medal was instituted in 1943 in the United Kingdom by Maria Dickin to honour the work of animals in war. It is a bronze medallion, bearing the words "For Gallantry" and "We Also Serve" within a laurel wreath, carried on a ribbon of striped green, dark brown and pale blue...

.

Carrier pigeons should not be confused with English Carrier

English Carrier

The English Carrier is a breed of fancy pigeon developed over many years of selective breeding. English Carriers, along with other varieties of domesticated pigeons, are all descendants of the Rock Pigeon...

s, which were once used many years ago to carry messages but are now bred primarily for their "carriage" and other show qualities.

Carrier pigeons historically carried messages only one way, to their home.