Types of money

In economics, money is a broad term that refers to any instrument that can be used in the resolution of debt. However, different types of money have different economic strengths and liabilities. Theoretician Ludwig von Mises made that point in his book The Theory of Money and Credit, and he argued for the importance of distinguishing among three types of money: commodity money, fiat money, and credit money. Modern monetary theory also distinguishes among different types of money, using a categorization system that focuses on the liquidity of money.

Commodity money
Main article: Commodity money
Commodity money is any money whose value comes from the commodity out of which it is made. The commodity itself constitutes the money, and the money is the commodity.[7] 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, etc. Since payment by commodity generally provides a useful good, commodity money is similar to barter, but is distinct because commodity money uses a single recognized unit of exchange.

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.

Banknotes from all around the world donated by visitors to the British Museum, London.

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.[7] 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.[7]
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.[8]
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.
Over the last two centuries, credit money has steadily risen as the main source of money creation, progressively replacing first commodity and then representative money. In many cases credit money has been converted to fiat money (see below), as governments have backed certain private credit instruments (first banknotes from central banks, then later certain types of deposits to banks), thus converting central banknotes to legal tender, and other types of notes (deposit certificates of less than a certain value) to a status not very different from fiat money, since they are backed by the power of the central government to redeem eventually with tax collection.
A particular problem with credit money is that its supply moves in line with the business cycle. When lenders are optimistic, notably when the debt level is low, they increase their lending activity which creates new money. This may also trigger inflation and bull markets. When creditors are pessimistic (for instance, when debt level is perceived as too high, or unwise lending activity in the past has resulted in situations where defaults are expected to follow), then creditors reduce their lending activity and money becomes "tight" or "illiquid." Bear markets, characterized by bankruptcies and market recessions, then follow.

Fiat money
Main article: Fiat money
Fiat money is any money whose value is determined by legal means, rather than the strict availability of goods and services which are named on the representative note.
Fiat money is created when a type of credit money (typically notes from a central bank, such as the Federal Reserve System in the U.S.) is declared by a government act (fiat) to be acceptable and officially-recognized payment for all debts, both public and private. Fiat money may thus be symbolic of a commodity or a government promise, though not a completely specified amount of either of these. Fiat money is thus not technically fungible or tradable directly for fixed quantities of anything, except more of the same government's fiat money. Fiat moneys usually trade against each other in value in an international market, as with other goods. An exception to this is when currencies are locked to each other, as explained below. Many but not all fiat moneys are accepted on the international market as having value. Those that are trade indirectly against any internationally available goods and services [7]. Thus the number of U.S. dollars or Japanese yen which are equivalent to each other, or to a gram of gold metal, are all market decisions which change from moment to moment on a daily basis. Occasionally, a country will peg the value of its fiat money to that of the fiat money of a larger economy: for example the Belize dollar trades in fixed proportion (at 2:1) to the U.S. dollar, so there is no floating value ratio of the two currencies.
Representative, credit, and fiat money all provide solutions to several limitations of commodity money. Depending on the laws, there may be little or no need to physically transport the money — an electronic exchange may be sufficient. Other types of moneys have as their sole use to be medium of exchange, so their supply is not limited by competing alternate uses. Credit and fiat monies can be created without limit in theory, so there is no limit on trade volumes.
Fiat money, if physically represented in the form of currency (paper or coins) can be easily damaged or destroyed. However, here 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.[9]. By contrast, commodity money which has been destroyed or lost is gone.
Paper currency is especially vulnerable to everyday hazards: from fire, water, termites, and simple wear and tear. Currency in the form of minted coins is more durable but a significant portion is simply lost in everyday use. In order to reduce replacement costs, many countries are converting to plastic currency. For example, Mexico has changed its twenty and fifty peso notes, Singapore its $2, $5, $10 and $50 bills, Malaysia with RM5 bill, and Australia and New Zealand their $5, $10, $20, $50 and $100 to plastic, both for the increased durability and because plastic may be easily specifically constructed for each denomination, thus making it impossible for counterfeiters to "lift" or raise the value of a bill by using the material of a bill of lesser value as a primary source to make a counterfeit note of higher value.
Some of the benefits of fiat money can be a double-edged sword. For example, if the amount of money in active circulation outstrips the available goods and services for sale, the effect can be inflationary. This can easily happen if governments print money without attention to the level of economic activity, or if successful counterfeiters flourish.
A criticism of credit and fiat moneys relates to the fact that their stabilities are highly dependent on the stability of the legal system backing the currency: should the legal system fail, so will the value of any type of money that depends on it. However, this situation is typical of the maintenance of the value of any promisory note system: if a guarantor creates money or wealth by means of any legal promise to provide goods or services in the future (as is the case with both credit and fiat type moneys), then any failure of a legal system which backs up the rights of the debt-holder to collect on the promise, will act to jeopardize the value of future promises.