Rules and terminology differ from country to country.
Several national styles had developed by the end of the Middle Ages, but some aspects carry over internationally.
In Canada, the restriction against women's bearing arms on a shield has been abrogated.
These were not heraldic in the medieval sense, as they were associated with military units, not individuals or families.
In heraldry, an escutcheon, or scutcheon, is the shield displayed in a coat of arms.
The escutcheon shape is based on the Medieval shields that were used by knights in combat.
Truly heraldic devices seem to have been first used in Carolingian times.
Seals and banners confirm that they were being used in the Flemish area of Europe during the reign of Charlemagne (768814 AD).
Although heraldry is nearly 900 years old, it is still in use.