Heraldry existed before there was a College of Arms. Heralds are first mentioned in the historical accounts about the time of the first crusade (ca. 1100).
By the late 12th century their importance had grown, coinciding with the development of armour for knights. At that time, distinctive markings easily distinguishable from a distance were essential for recognising combatants whose faces were fully covered by helmets.
These markings were placed on surcoats worn over the armour (the derivation of the term coat of arms) and soon were passed down from father to son, with families becoming identified by the markings.
It was the responsibility of the heralds, who also served as military staff officers, diplomats and messengers (they were often the only members of a household who could read), and masters of ceremony at pageants and tournaments (where they were allowed to keep any broken armour), to keep track of which family used which emblems and ensure that no two families used the same arms. Because the coats of arms were hereditary, the herald's expertise has long covered lines of descent.
In 1484, King Richard III institutionalised the already centuries-old tradition of heraldry by incorporating the College of Arms in London. It is the oldest existing and one of the few remaining heraldic authorities in the world.
Today, as they were then, the members of the College are part of the Royal Household and are headed by the Earl Marshal of England, the Duke of Norfolk. The heralds are responsible for ceremonial, armorial and genealogical matters, including organising coronations, openings of Parliament, state funerals, and the granting of new arms in all countries where the Queen is head of state, with the exceptions of Scotland and Canada, each of which has its own heraldic authority. They are also entitled to conduct a private heraldic and genealogical practice.
As a result of the heralds' work over the centuries, the College of Arms has accumulated - and continues to add to - an extensive and unique archive of official records and documents relating to family histories and arms.
As a corollary, the College has its own conservation and bookbinding department, which is now widely used by other repositories of valuable manuscripts and books. And because grants of arms are in perpetuity, and therefore must be issued in durable form, the College has on staff scriveners and artists, as well as secretaries and researchers, to produce illuminated letters patent on vellum (sheepskin). These objects are virtually works of art in themselves.
The College of Arms has occupied the same site since 1555 - the original building (but not its contents, which were saved) was destroyed during the Great Fire of 1666 and was rebuilt in the 1670s.
The College is not a school. It has neither faculty nor students and does not offer courses.