A coat of arms is a unique heraldic design on an escutcheon (i.e. shield), surcoat, or tabard. A surcoat, and subsequently a coat of arms was used by medieval knights to cover, protect, and identify the wearer. Thus these are sometimes called coat armory. The coat of arms on an escutcheon forms the central element of the full heraldic achievement which consists of shield, supporters, crest, and motto. The design is a symbol unique to an individual person or family (except in the UK), corporation, or state. Such displays are commonly called armorial bearings, armorial devices, heraldic devices, or simply arms.