Feathers are epidermal growths that form the distinctive outer covering, or plumage, on dinosaurs, both avian and some non-avian, and possibly other archosauromorphs. They are considered the most complex integumentary structures found in vertebrates and a premier example of a complex evolutionary novelty. They are among the characteristics that distinguish the extant birds from other living groups.
Although feathers cover most of the bird's bodies, they arise only from certain well-defined tracts on the skin. They aid in flight, thermal insulation, and waterproofing. In addition, coloration helps in communication and protection. Plumology is the name for the science that is associated with the study of feathers.