On a coat of arms, the crest is found above the shield, usually on top of a helmet. The crest can be used alone as a symbol for the holder/family or a shortcut for the coat of arms.

So seriously that one must register a coat-of-arms (which applies only to an individual, not a family), and the cost of registration increases as you add various elements (like that helmet).

BALMEDIE, Scotland — Real-estate mogul Donald Trump finally has the official Scottish coat of arms he longed for, it was announced Tuesday. The insignia will be used to promote his monolithic… ...

Crests hold more historical significance than you might think. In medieval countries with a monarchy, the king would bestow a family crest or coat of arms on higher-class families and his knights.