The origin of the Coat of Arms was a jacket or tabard worn by a mediaeval Knight over his armour in order to identify himself. Nowadays the expression "Coat of Arms" is generally applied to what is officially called an "Achievement", which consists of various parts: a shield, helmet, mantling, wreath, crest, motto and sometimes supporters and decorations.
There is a widespread misconception that a family or a clan can have a family or clan Coat of Arms. Many heraldic and clan web sites and other media suggest that a person has the right to use the family or clan Arms. This is completely incorrect.
A Coat of Arms belongs only to one individual person and can only be used by that person and no one else. In order for a person to be able to use a Coat of Arms it is necessary for that individual person to apply for a personal Coat of Arms to be granted to him or her .
What is permitted is for a member of a clan to use the clan crest . Usually what is referred to as the clan Coat of Arms is in fact the personal Arms of the chief of the clan which can only be used by the chief.