Heraldry is a special system of identification that developed during the Middle Ages in order to help distinguish fully armored knights on the battle and tournament field. Its remote origins fairly obviously lie partly in the military and national symbols and insignia that were used in ancient Egypt and Rome and even in England, and partly in the individual designs of personal seals that have been found as far back as ancient Mesopotamian society. However, the immediate origins of medieval heraldry probably lie in knights painting personal designs on their shields and on their clothing to help their allies recognize them. These distinguishing devices were meant to be seen at a distance, so large designs and bright contrasting colors were used. Gradually, as not only warriors but also clergy and noble women (and even towns and organizations) adopted heraldic devices, a system of fixed rules and convention for design developed in order to regulate them. By the middle of the Thirteenth Century heraldry with its rules was firmly in place along with a method of describing heraldic designs in words, called "blazoning."

The Bayeux Tapestry is often considered to be a very important pre-heraldic document. Although the designs on the shields are not arms proper (knights are seen in part with one shield design and seen in other parts of the tapestry with different ones.), in one scene showing the Battle of Hastings, William is depicted raising his helmet to show that he was not dead. This shows the need for a system of identification like heraldry.