Commonly known as a Family Shield or coat of arms, that is the main body or field of the plaque, which can be in a few shapes de[pending on sex, a woman has a losenge shape, the crest is the part abovew the shield that depicts the rank of the bearer. That is a basic description, not all coats of arms (armoral bearings) have a crest, the arms of a Bishop would have a mytre, the arms of a Duke a coronet maybe, the arms of an eldest son may have one crest and the second son another, it is very complex. There are various partys of a shield (to simplify the explanation) that depict different trades, standing, events, there are also sup[porters, like the lion and the unicorn on the Royal Coat of arms, not all Armoral bearings have those. There is also the 'motto' as a layman would call it, again, not all have a 'motto' Elton John has a yellow brick road and a reference to watford Town as I recall.