Heraldry refers to designs with a coat of arms, crests, banners, and flags that have insignia with very specific symbols, identifying exclusive elements of a particular family’s or group. Heraldry is considered both an art and a science, and is intimately linked with the history of Europe. (That said, many other cultures had a similar symbol-based system to identify people and their origins, such as the beautiful Japanese “Mon” symbols).
Heraldry is a very is old art, dating from the 13th century when the feudal system was in place in Europe. Knights were outfitted from head to toe in heavy armor, including helmets and shields. To identify them as friend or foe, each knight’s armor was decorated with elements relating to where he came from and who he was. This is the origin of heraldry. To get an idea of what this sort of head-to-toe insignia might have looked like, think of the dashing Beefeaters (the Yeoman guards at Buckingham Palace), with their bright and colorful costumes.
During the middle ages, a herald was a person who worked in the court and was in charge of managing the heraldry, and all that went with it. Excerpt from my Modern Heraldry Lettering lesson, available from PaperClothScissors