Privy mark
Encyclopedia
Coin
A coin is a piece of hard material that is standardized in weight, is produced in large quantities in order to facilitate trade, and primarily can be used as a legal tender token for commerce in the designated country, region, or territory....
for the purpose of identifying the mint
Mint (coin)
A mint is an industrial facility which manufactures coins for currency.The history of mints correlates closely with the history of coins. One difference is that the history of the mint is usually closely tied to the political situation of an era...
, moneyer, or some other aspect of the coin's production or origin, for control purposes. Nowadays it is mainly used as a design and marketing feature.