Coin currency is a standardized, minted form of currency used in many countries around the world. It is a common method of payment and can be used to pay for goods, services, or money transfers.
The obverse (heads) of a coin is usually engraved with an image of a monarch, other authority, or a national emblem, while the reverse (tails) is engraved with information such as the year of minting or the type of the coin. Most coins have images of these people or objects on their obverse, but only some Chinese and Canadian coins, the pre-2008 British 20p coin, the post-1999 American quarter, and most Japanese coins have these images on both sides of the coin.
Exceptions to this rule exist for bullion coins made of gold, silver, or copper. The American Gold Eagle, the British Sovereign, and the Canadian Gold Maple Leaf are examples of such bullion coins. These coins typically have face values that are higher than their content value.
The first coins to appear in Antiquity were rough lumps of bronze known as aes rude, the weight of which was regulated by law. They were the precursors of standard weights and a system of coinage that dominated the ancient world from the late Bronze Age to the early Iron Age.
These coins were minted in the form of drachmas and pegasi, and it is possible that they served as a medium of exchange in both the East and the West. These coins were largely based on a standard weight of about three grams, but they differed in obverse and reverse types. In some cases they were patterned with a die design, in others they were struck by a hammer and chisel.
Before coins were standardized, the weights and values of bronze ingots varied greatly across regions. For example, a single bronze ingot from Crete might be as much as 50 percent lighter than an identical ingot from the same region in the Near East.
By the early fifth century bc, however, these different weights and weight units were standardized and coins began to appear in large quantities. These were the forerunners of a system of standardized coinage that was to spread throughout the Greek world and to influence the economies of many other countries in Europe, Asia, and Africa.
Early coins tended to be of a similar weight and were largely unmarked, but they sometimes had inscriptions on them. These inscriptions were usually intended to convey some form of information about the issuing authority or to make it easier to distinguish one coin from another.
Some coins had milled or reeded edges, originally designed to help detect clipping of the edge. This was a practice that often reduced the value of circulating coins, especially British sterling silver ones.
A shortage of silver caused by war and economic changes meant that circulating coins were often debased, or “shaved” or clipped, in order to reduce the total amount of silver in them. This was known as Gresham’s law.