The first coats of arms were assumed by the knights themselves. That is, they came up with their own marks, but this often led to confusion when several people would show up with the same mark. So the king put someone in charge of keeping track of who was who and writing down which marks belonged to which people. That person was called the Herald, and the science of creating coats of arms and tracking their use was called heraldry. People who wanted to create a new coat of arms had to have it approved by the Herald and soon there were so many that the Herald had to ride from town to town to hear about new coats of arms and make decisions to resolve conflicts. These visitations led to the court of chivalry, and before long, the Herald himself would assign a coat of arms to a new knight or member of the noble class, and the court of chivalry would make decisions about changes and conflicts. There are even some records of cases when the king himself assigned a coat of arms to someone by royal decree.
The knight had his coat of arms on his shield.
the purpose of the coat of arms on a knight were so he could be identified on the battlefield.
Coat of arms of the Gambia was created in 1964.
Coat of Arms of Connecticut was created in 1931.
Coat of arms of Montserrat was created in 1909.
Coat of arms of Toronto was created in 1998.
Coat of arms of Sydney was created in 1996.
Coat of arms of Bratislava was created in 1436.
Coat of arms of Copenhagen was created in 1661.
Coat of arms of Ottawa was created in 1954.
Coat of arms of Nunavut was created in 1999.
Coat of arms of Belgrade was created in 1932.