Types of money

Currently, most modern monetary systems are based on fiat money. However, for most of history, almost all money was commodity money, such as gold and silver coins. As economies developed, commodity money was eventually replaced by representative money, such as the gold standard, as traders found the physical transportation of gold and silver burdensome. Fiat currencies gradually took over in the last hundred years, especially since the breakup of the Bretton Woods system in the early 1970s.

Commodity money


Main article: Commodity money
Commodity money value comes from the commodity out of which it is made. The commodity itself constitutes the money, and the money is the commodity. Examples of commodities that have been used as mediums of exchange include gold, silver, copper, rice, salt, peppercorns, large stones, decorated belts, shells, alcohol, cigarettes, cannabis, candy, barley, etc. These items were sometimes used in a metric of perceived value in conjunction to one another, in various commodity valuation or Price System economies. Use of commodity money is similar to barter, but a commodity money provides a simple and automatic unit of account for the commodity which is being used as money.

Representative money


Main article: Representative money
Representative money is money that consists of token coins, other physical tokens such as certificates, and even non-physical "digital certificates" (authenticated digital transactions) that can be reliably exchanged for a fixed quantity of a commodity such as gold, silver or potentially water, oil or food. Representative money thus stands in direct and fixed relation to the commodity which backs it, while not itself being composed of that commodity.
The gold standard, based on paper notes that are normally freely convertible into fixed quantities of gold, is the most common form of representative money. It was adopted by most of the industrialized countries during the 18th and 19th centuries.

Fiat money


Banknotes from all around the world donated by visitors to the British Museum, London.
Main article: Fiat money
Fiat money or fiat currency is money whose value is not derived from any intrinsic value or guarantee that it can be converted into a valuable commodity (such as gold). Instead, it has value only by government order (fiat). Usually, the government declares the fiat currency (typically notes and coins from a central bank, such as the Federal Reserve System in the U.S.) to be legal tender, making it unlawful to not accept the fiat currency as a means of repayment for all debts, public and private.
Fiat money may be symbolic of a commodity (e.g. the UK Pound sterling), but it does not carry a guarantee that it can be traded directly for fixed quantities of anything, other than the same government's money. Fiat monies usually trade against each other in an international market, and can change value, as with other goods. Thus the number of U.S. dollars or Japanese yen which are equivalent to each other, or to a gram of gold, are all market decisions which change from moment to moment. An exception to this is when a government implements a fixed exchange rate, and locks the value of its currency versus the currency of another (usually larger) trading partner. For example, the Belize dollar trades in fixed proportion (at 2:1) to the U.S. dollar.
Fiat money, if physically represented in the form of currency (paper or coins) can be accidentally damaged or destroyed. However, fiat money has an advantage over representative or commodity money, in that the same laws that created the money can also define rules for its replacement in case of damage or destruction. For example, the U.S. government will replace mutilated Federal Reserve notes (U.S. fiat money) if at least half of the physical note can be reconstructed, or if it can be otherwise proven to have been destroyed. By contrast, commodity money which has been lost or destroyed cannot be recovered.

Credit money


Main article: Credit money
Credit money is any claim against a physical or legal person that can be used for the purchase of goods and services. Credit money differs from commodity and fiat money in two ways: It is not payable on demand (although in the case of fiat money, "demand payment" is a purely symbolic act since all that can be demanded is other types of fiat currency) and there is some element of risk that the real value upon fulfillment of the claim will not be equal to real value expected at the time of purchase.
This risk comes about in two ways and affects both buyer and seller. First it is a claim and the claimant may default (not pay). High levels of default have destructive supply side effects. If manufacturers and service providers do not receive payment for the goods they produce, they will not have the resources to buy the labor and materials needed to produce new goods and services. This reduces supply, increases prices and raises unemployment, possibly triggering a period of stagflation. In extreme cases, widespread defaults can cause a lack of confidence in lending institutions and lead to economic depression. For example, abuse of credit arrangements is considered one of the significant causes of the Great Depression of the 1930s.
The second source of risk is time. Credit money is a promise of future payment. If the interest rate on the claim fails to compensate for the combined impact of the inflation (or deflation) rate and the time value of money, the seller will receive less real value than anticipated. If the interest rate on the claim overcompensates, the buyer will pay more than expected. The process of fractional-reserve banking has a cumulative effect of money creation by banks.