Money was historically an emergent market phenomenon that possessed intrinsic value as a commodity; nearly all contemporary money systems are based on unbacked fiat money without use value. Its value is consequently derived by social convention, having been declared by a government or regulatory entity to be legal tender; that is, it must be accepted as a form of payment within the boundaries of the country, for "all debts, public and private", in the case of the United States dollar.
A nickel is a five-centcoin struck by the United States Mint. Composed of cupronickel (75% copper and 25% nickel), the piece has been issued since 1866. Its diameter is 0.835 inches (21.21 mm) and its thickness is 0.077 inches (1.95 mm).
The silver half dime, equal to five cents, was issued from 1792 to 1873 before today's cupronickel version. The American Civil War caused economic hardship, driving gold and silver from circulation; in response, in place of low-value coins, the government at first issued paper currency. In 1865, Congress abolished the five-cent fractional currency note after Spencer M. Clark, head of the Currency Bureau (today the Bureau of Engraving and Printing), placed his own portrait on the denomination. After the successful introduction of two-cent and three-cent pieces without precious metal, Congress also authorized a five-cent piece consisting of base metal; the Mint began striking this version in 1866. The initial design of the Shield nickel was struck from 1866 until 1883, then was replaced by the Liberty Head nickel. The Buffalo nickel was introduced in 1913 as part of a drive to increase the beauty of American coinage. (Full article...)
The apsar (Abkhaz: аԥсар, āpsār) is a currency of Abkhazia. So far, coins in denominations of 1, 2, 3, 5, 10, 20, 25, 50, and 100 apsars and banknotes in denominations of 10, 25, 100, and 500 apsars have been issued. While the coins and banknotes are legal tender in the Republic of Abkhazia, their usage is very limited, and they are mostly made for collectors. In Abkhazia, the Russian ruble is used in practice. The first apsar coins were introduced in 2008.
Image 9A 640 BC one-third staterelectrum coin from Lydia. According to Herodotus, the Lydians were the first people to introduce the use of gold and silver coins. It is thought by modern scholars that these first stamped coins were minted around 650 to 600 BC. (from Money)