The chicken (Gallus gallus domesticus), a subspecies of the red junglefowl, is a type of domesticated fowl, originally from Southeastern Asia. Rooster or cock is a term for an adult male bird. A younger male may be called a cockerel; a male that has been castrated is a capon. The adult female bird is called a hen. "Chicken" was originally a term only for an immature, or at least young, bird, but thanks to its usage on restaurant menus has now become the most common term for the subspecies in general, especially in American English. In older sources, common fowl or domestic fowl were typically used for this.

Originally raised for cockfighting or for special ceremonies, chickens were not kept for food until the Hellenistic period (4th–2nd centuries BCE). Humans now keep chickens primarily as a source of food (consuming both their meat and eggs).