What Is a Coin?

Coin currency

A coin is a piece of hard material, generally metal in the shape of a disk. It is typically minted by governments for use as money in transactions. Along with banknotes, coins make up the cash forms of all modern money systems. Coins are usually used for lower-valued units, while higher-value notes are commonly found on banknotes. A coin’s value depends on its intrinsic worth and the market exchange price of its component metal, or its historical and symbolic importance (see Numismatics).

Historically, coins have been made in a wide variety of shapes, sizes, and materials. The most common are circular but they can also be square, polygonal, or even have wavy edges. A spherical coin that is turned right-side-up shows an image on the obverse, which is colloquially known as heads. If the coin is turned over and viewed from the other side, it displays a reverse image, or tails. A coin’s orientation is determined by a simple test: if the obverse image is shown right-side up and turning it left or right reveals that the reverse image is also right-side-up, it is said to be medallicly (or obversely) oriented. This is the case for most Euro and pound sterling coins, as well as all American coins.

Early coins were often quite rough lumps of bronze (aes rude) or of silver (aes argentum). But the invention of true coinage allowed the production of more regular-weight coins. Gold rings served as a general currency in Egypt from the 4th millennium bc, complemented by gold and silver bars of standardized weight that were divided into segments for trade. Julius Caesar’s accounts of his battles in Britain during the 55 and 54 bc, where he used fractional iron spits (obeloi) that were weighed at the Heraeum at Argos, suggest that the idea of coinage spread from the Mediterranean to the rest of Europe.

The standardization of coinage was greatly helped by the discovery that certain alloys of copper and silver lent themselves to distinctive, easily identifiable, and very durable coins. The earliest coins were standardized in the 5th century bc by the Roman Empire with the introduction of the denarius and later the assinio; these were followed by silver dinars in the Islamic world.

Inflation and debasement of coins can severely impact a country’s currency. For example, in the United States, one-cent coins minted before 1982 formerly contained more copper than they did today, and the metals in the one- and five-cent pieces that were minted after 1982 became less valuable than their face value as time passed.

The coins most in circulation today are mostly made of a mix of copper and nickel and have the phrase “In God We Trust” and the motto E Pluribus Unum on the front and the American eagle on the back. They are worth one cent each. In addition, some United States coins have a picture of Abraham Lincoln on one side and the Lincoln Memorial on the other.