Authentication - Authoritative determination of the genuineness of a coin.
Circulating Coin - A coin that has been issued by a bank.
Grade - A carefully constructed series of guidelines to determine the condition and therefore the rarity and value of a coin.
Mint mark - A letter or symbol, indicating the mint of origin.
Mule - A coin, token or medal whose obverse design is not matched with its reverse.
Numismatics - The science, study or collecting of coins or similar objects.
Proof Coin - A carefully struck coin using special dies, with frosted images on a mirror-like background. Proof is a method of manufacture, not a condition or grade.
Uncirculated Coin - A coin which has not been distributed or used as currency.