A coat of arms is an heraldic visual design on an escutcheon (i.e., shield), surcoat, or tabard. The coat of arms on an escutcheon forms the central element of the full heraldic achievement which in its whole consists of shield, supporters, crest, and motto. A coat of arms is traditionally unique to an individual person, family (except in the United Kingdom), state, organisation or corporation.
The ancient Greek hoplites used individual insignia on their shields. The ancient Romans used similar insignia on their shields, but these identified military units. The first evidence of medieval coats of arms has been attributed to the 11th century Bayeux Tapestry in which some of the combatants carry shields painted with crosses. However, that heraldic interpretation remains controversial.
Coats of arms came into general use by feudal lords and knights in battle in the 12th century. By the 13th century, arms had spread beyond their initial battlefield use to become a flag or emblem for families in the higher social classes of Europe, inherited from one generation to the next. Exactly who had a right to use arms, by law or social convention, varied to some degree between countries. In the German-speaking regions both the aristocracy and "burghers" (non-noble free citizens) used arms, while in most of the rest of Europe they were limited to the aristocracy. The use of arms spread to the clergy, to towns as civic identifiers, and to royally chartered organizations such as universities and trading companies. Flags developed from coats of arms, and the arts of vexillology and heraldry are closely related. The coats of arms granted to commercial companies are a major source of the modern logo.