Heraldry is a discipline relating to the design, display and study of armorial bearings, as well as related disciplines, such as vexillology, together with the study of ceremony, rank and pedigree. Armory, the best-known branch of heraldry, concerns the design and transmission of the heraldic achievement. The achievement, or armorial bearings usually includes a coat of arms on a shield, helmet and crest, together with any accompanying devices, such as supporters, badges, heraldic banners and mottoes.

In heraldic achievements, the helmet or helm is situated above the shield and bears the torse and crest. The style of helmet displayed varies according to rank and social status, and these styles developed over time, in step with the development of actual military helmets. In some traditions, especially German and Nordic heraldry, two or three helmets may be used in a single achievement of arms, each representing a fief to which the bearer has a right. For this reason, the helmets and crests in German and Nordic arms are considered essential to the coat of arms and are never separated from it.