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A crest is a component of an heraldic display, so called because it stands on top of a helmet, as the crest of a jay stands on the bird's head.
The earliest heraldic crests were apparently painted on metal fans, and usually repeated the coat of arms painted on the shield, a practice which was later discontinued with perhaps one unique exception, found here. Later they were sculpted of leather and other materials. Today, the crests of new Knights of the Garter and Bath are carved from lime wood by sculptor Ian G Brennan for display in St George's Chapel at Windsor Castle (Garter) and Henry VII Lady Chapel in Westminster Abbey (Bath).
Originally, the crest was often "continued into the mantling," but today the crest normally stands within a wreath of cloth, called a torse, in the principal colors of the shield (the liveries). Various kinds of coronet may take the place of the torse, though in some unusual circumstances the coronet sits atop a torse, and is either defined as all or part of a crest. The most frequent crest-coronet is a simplified form of a ducal coronet, with four leaves rather than eight. Towns often have a mural crown, i.e. a coronet in the form of embattled stone walls.
Objects frequently borne as crests include animals, especially lions, normally showing only the fore half; human figures, likewise often from the waist up; hands or arms holding weapons; bird's wings. In Germany and nearby countries, the crest often repeats the liveries in the form of a tall hat, a fan of plumes in alternating colors, or a pair of curving horns. The horns may have a hole in the tip to hold a cluster of plumes or flowers, and because of this have been imported to English heraldry at least once as elephant's trunks.
Crests are not normally borne by women or clergy, because they do not participate in war or tournaments and thus would not have a helm on which to wear it. An exception is the reigning queens of England or Britain, whose armorial display is indistinguishable from that of kings.
While it is not strictly correct, there is a convention that a crest may be displayed within a belt and buckle by persons other than its legal bearer, signifying non-ownership. There is a widespread misconception, due in part to Victorian stationers' marketing of engraved letterheads, that a crest and a coat of arms belong to everyone with the same family name; but usage by persons not descended from the original grantee constitutes usurpation. Bogus "family crests" continue to be sold to the gullible by heraldic "bucket shops."