The main cause of hyperinflation is a massive imbalance between the supply and demand of a certain currency or type of money, usually due to a complete loss of confidence in the currency similar to a bank run. First, the enactment of legal tender laws prevent discounting the value of paper money vis-a vis gold, silver or a hard currency, by forcing acceptance of a paper money which lacks intrinsic value. If the entity responsible for printing a currency then promotes excessive money printing, with other factors contributing a reinforcing effect, hyperinflation usually occurs. Often the body responsible for printing the currency cannot physically print paper currency faster than the rate at which it is devaluing, thus neutralising their attempts to stimulate the economy

Hyperinflation is generally associated with paper money because the means to increasing the money supply with paper money is the simplest: add more zeroes to the plates and print, or even stamp old notes with new numbers. There have been numerous episodes of hyperinflation, followed by a return to "hard money". Older economies would revert to hard currency and barter when the circulating medium became excessively devalued, generally following a "run" on the store of value.

Unlike inflation, which is sometimes seen as a necessary evil in a healthy economy, hyperinflation is always regarded as destructive. It effectively wipes out the purchasing power of private and public savings, distorts the economy in favor of extreme consumption and hoarding of real assets, causes the monetary base whether specie or hard currency to flee the country, and makes the afflicted area anathema to investment.

The aftermath of hyperinflation is equally complex. As hyperinflation has always been a traumatic experience for the area which suffers it, the next policy regime almost always enacts policies to prevent its recurrence. Often this means making the central bank very aggressive about maintaining price stability as is the case with the German Bundesbank, or moving to some hard basis of currency such as a currency board. Many governments have enacted extremely stiff wage and price controls in the wake of hyperinflation, which is, in effect, a form of forced savings.

A 500,000,000,000 (500 billion) Yugoslav dinar banknote circa 1993, the largest nominal value ever officially printed in Yugoslavia, the final result of hyperinflation. Photo courtesy of National Bank of Serbia (www.nbs.yu)

For a variety of reasons, governments have occasionally resorted to printing money to meet their expenses. During hyperinflation, the monetary authority can't even do that as it becomes a net loss. Those holding government debt, directly or indirectly, have less buying power. Theories of hyperinflation generally look for a relationship between seignorage and the inflation tax. In both Cagan's model and the neo-classical models, a crucial point is when the increase in money supply or the drop in basic money stock makes it impossible for a government to improve its financial position. Thus when fiat money is printed, government obligations that are not denominated in money increase in cost by more than the value of the money created.

From this, it might be wondered why any state would engage in actions that cause or continue hyperinflation. One reason is that often the alternative to hyperinflation is either depression or military defeat. In late 2001, the Argentine peso collapsed in value. Rather than printing sufficient cash for the public to carry, which they feared would start a run on the banks, the government took the peso off its dollar peg. Many international economists predicted that they would have to get a new loan from the IMF and impose shock therapy in order to avoid hyperinflation. Currency controls were imposed, tariffs were instituted, and the economy was allowed to fall into a severe recession during which unemployment hit 25%, homelessness and crime spiraled upwards, and the poverty rate peaked at over 50%.

The root cause is a matter of more dispute. In both classical economics and monetarism, it is always the result of the monetary authority irresponsibly borrowing money to pay all its expenses. These models focus on the unrestrained seignorage of the monetary authority, and the gains from the inflation tax. In Neoliberalism, hyperinflation is considered to be the result of a crisis of confidence. The monetary base of the country flees, producing widespread fear that individuals will not be able to convert local currency to some more transportable form, such as gold or an internationally recognized hard currency. This is a quantity theory of hyper-inflation.

Hyperinflation is regarded as a complex phenomenon and one explanation may not be applicable to all cases. However, in both of these models, whether loss of confidence comes first, or central bank seignorage, the other phase is ignited. In the case of rapid expansion of the money supply, prices rise rapidly in response to the increased supply of money relative to the supply of goods and services, and in the case of loss of confidence, the monetary authority responds to the risk premiums it has to pay by "running the printing presses".

In the United States of America, hyperinflation was seen during the Revolutionary War and during the Civil War, especially on the Confederate side. Many other cases of extreme social conflict encouraging hyperinflation can be seen, as in Germany after World War I, Hungary at the end of World War II and in Yugoslavia in late 1980s just before break up of the country.

Less commonly, hyperinflation may occur when there is debasement of the coinage - wherein coins are consistently shaved of some of their silver and gold, increasing the circulating medium and reducing the value of the currency. The "shaved" specie is then often restruck into coins with lower weight of gold or silver. Historical examples include Ancient Rome, China during the Song Dynasty, and the United States beginning in 1933. When "token" coins begin circulating, it is possible for the minting authority to engage in fiat creation of currency.