A private currency is a currency issued by a private entity, be it an individual, a commercial business, a nonprofit or decentralized common enterprise. It is often contrasted with fiat currency issued by governments or central banks. In many countries, the issuance of private paper currencies and/or the minting of metal coins intended to be used as currency may even be a criminal act such as in the United States (18 U.S. Code § 486). Digital cryptocurrency is sometimes treated as an asset instead of a currency. Cryptocurrency is illegal as a currency in a few countries (mainly in West Asia and North Africa).
Today, there are over four thousand privately issued currencies in more than 35 countries. These include commercial trade exchanges that use barter credits as units of exchange, private gold and silver exchanges, local paper money, computerized systems of credits and debits, and digital currencies in circulation, such as digital gold currency.
In the United States, the Free Banking Era lasted between 1837 and 1866, when almost anyone could issue paper money. States, municipalities, private banks, railroad and construction companies, stores, restaurants, churches and individuals printed an estimated 8,000 different types of money by 1860. If an issuer went bankrupt, closed, left town, or otherwise went out of business, the note would be worthless. Such organizations earned the nickname of "wildcat banks" for a reputation of unreliability; they were often situated in remote, unpopulated locales said to be inhabited more by wildcats than by people. The National Bank Act of 1863 ended the "wildcat bank" period. See also: History of free banking.
In Australia, private currency had first been used since the arrival of European settlers in 1788, and into the early years of Federation before the Bank Notes Tax Act 1910 effectively shut down the circulation of private currencies by imposing a 10% tax on the practice, making it economically prohibitive.