Heraldry

Heraldry (symbols identifiable with individuals or families) originated as a way to identify knights in battle or in tournaments. With the advent of the "great" or "barrel" helm (ca. early 13th century) an individual's face became concealed. It therefore became necessary to create a method to distinguish ally from enemy.
Heraldic symbols ranged from simple geometric shapes such as chevrons, to more elaborate drawings of real or mythological animals. As with the honor of becoming a knight, heraldic insignia became hereditary, being passed on from father to son, or with the family name. Eventually heraldic symbols also came to signify kingdoms, duchies, or provinces as a medieval forerunner to our modern national flags. 

Heraldic symbols were often worn on the knight's surcoat (thus the term "coat of arms"), shield, helmet, or on a banner (standard) that could serve as a rallying point for knights and others scattered in the chaos of battle. The standard was always to be elevated as long as the battle continued, and therefore was guarded well. A standard taken down would signal the allied combatants that the cause was lost and it was time to flee the field of combat.
Today heraldry is usually associated with individual families' coat of arms. Researching heraldry has become a hobby for many people. The art and science of heraldry, with its medieval beginnings, is still alive and well in our modern world.