The chicken (Gallus gallus domesticus) is a type of domesticated fowl, a subspecies of the red junglefowl. It is one of the most common and widespread domestic animals, with a total population of more than 19 billion as of 2011. There are more chickens than any other bird or domesticated fowl.[1] Humans keep chickens primarily as a source of food (consuming both their meat and eggs) and, more rarely, as pets.