The primary element of a heraldic achievement is the shield, or escutcheon, upon which the coat of arms is depicted. All of the other elements of an achievement are designed to decorate and complement these arms, but only the shield of arms is required. The shape of the shield, like many other details, is normally left to the discretion of the heraldic artist, and many different shapes have prevailed during different periods of heraldic design, and in different parts of Europe.