Chickens, e.g. are a type of bird and FOWL. They are members of the order Galliformes, which includes other domesticated birds such as turkeys, pheasants, quail, and guineafowl. Chickens are one of the most common and widespread domestic animals, with a population of more than 24 billion as of 2018. They are primarily kept for their eggs and meat, and are also used for cockfighting and feather plucking.