A coin is usually a piece of hard material, generally metal, usually in the shape of a disc, and most often issued by a government. Coins are used as a form of money in transactions of various kinds, from the everyday circulation of the United States quarter, to the storage of vast amounts of bullion. In the present day, coins and banknotes make up the cash forms of all modern money systems. Coins made for circulation (general monetized use) are usually used for lower-valued units, and banknotes for the higher values; also, in most money systems, the highest value coin is worth less than the lowest-value note. The face value of circulation coins is usually higher than the gross value of the metal used in making them. (wikipedia)