Currency is made up of coins and bills or federal reserve notes. These coins are usually made of copper or nickel or a combination of both. Different materials, such as steel have been used in the past. All of these coins are token coins. This means that the value of the coin is more than the value of the metal used in making the coin.
Coins make up about nine percent of the currency in the United States today.
Most currency is in the form of federal reserve notes. In the past there have also been notes issued in denominations of 2 and over 100 dollars. The notes are printed on special paper with special ink to avoid counterfeiting. There are also United states notes in denominations of 100 dollars only. The Treasury Department deals with matters concerning money.