Alloy: A mixture of two or more metals to create a material with specific properties.

Bronze: Alloy of copper and tin, widely used in lower denomination coins.

Clad Coinage: Coins that have a core and outer layer made of different metals.

Coin: Flat piece of metal issued by the government as money.

Commemorative: A special coin issued to honor an outstanding person, place, or event.

Copper: Reddish metal used pure or in alloys. Oxidizes forming verdigris (copper carbonate).

Counterfeit: A fake coin made to deceive people into thinking it's genuine.

Denomination: The different values of money, such as 1 dollar, 5 cents, etc.

Die: An engraved stamp used for impressing a design upon a blank piece of metal to make a coin.

Edge: The outer border of a coin, considered the "third side" (not to be confused with "rim").

Error: An improperly produced coin, overlooked in production, and later released into circulation.

Face Value: The sum for which a coin can be spent or exchanged as opposed to its collector value.

Gold: Precious metal used in coinage. Measured in karats (24k = pure gold). Very resistant to corrosion.

Grade: Rating which indicates how much a coin has worn from circulation.

Intrinsic Value: Current market value of the precious metal in a coin.

Legal Tender: Coins or currency issued by a government as official money.

Legend: Principal lettering on a coin.

Mint: A place where coins of a country are manufactured under government authority.

Mint Mark: A small letter on a coin identifying which facility struck the coin.

Mint State: Same as uncirculated - a coin that has not been released into circulation.

Mintage: The quantity of coins produced.

Numismatics: The study and collecting of things that are used as money, including coins, tokens, and medals.

Obverse: The front (or "heads") side of a coin.

Patina: Surface layer that forms naturally on metals through oxidation, especially visible on copper and bronze coins.

Proof: A specially produced coin made from highly polished blanks and dies, often struck more than once.

Reverse: The back (or "tails") side of a coin.

Series: A collection of coins that contains all date and mint marks of a specific design and denomination.

Silver: Precious metal widely used historically in coinage. Tarnishes over time creating patina.

Strike: The process of stamping a coin blank with a design.

Uncirculated: A coin that has not been used in everyday commerce and retains its original mint luster.

Variety: A minor change from the basic design type of a coin.