A chicken is a domesticated bird used for food, feathers and eggs, and a hen is the female of this species. The term "chicken" also describes a young bird of this species under 1 year old. The term "hen" is also used to describe the female of any bird.
The chicken was domesticated around 7,000 to 10,000 years ago. The origin of the bird's wild ancestors may have come from Southeast Asia. Wild chickens known as red jungle fowl, or Gallus Gallus, still exist in this area, and this bird exhibits the same behavior as domesticated chickens. The males have red waddles and a comb, and the females cluck just like barnyard chickens. Pictures of the domesticated chicken have even been found in tombs in Egypt. Throughout history, chickens have been worshipped, used for ritual sacrifice and brought to the dinner table.
Genome mapping has shown that there may have been more then one contributor to the domestication of the bird, but how much the other three species have contributed may never be known. Continuous genetic selection by breeders has provided different types of chickens. Some chickens lay more eggs, while others are larger, making for breeds that are large and meaty.