In trade, barter (derived from baretor) is a system of exchange where participants in a transaction directly exchange goods or services for other goods or services without using a medium of exchange, such as money. Economists distinguish barter from gift economies in many ways; barter, for example, features immediate reciprocal exchange, not delayed in time. Barter usually takes place on a bilateral basis, but may be multilateral (i.e., mediated through a trade exchange). In most developed countries, barter usually only exists parallel to monetary systems to a very limited extent. Market actors use barter as a replacement for money as the method of exchange in times of monetary crisis, such as when currency becomes unstable (e.g., hyperinflation or a deflationary spiral) or simply unavailable for conducting commerce.
Some businesses that may not directly barter with customers may swap goods or services through membership-based trading exchanges such as ITEX or International Monetary Systems (IMS). By joining a trading network (which often charges fees), members can trade with other members for barter "dollars." Each transaction is subject to a minimal fee; the exchange facilitates the swap and manages the tax components of bartering such as issuing 1099-B forms to participating members. You may find a nearby exchange through the International Reciprocal Trade Association (IRTA) Membership Directory. Before you sign up and pay for a membership, however, make sure that members offer the types of goods and services you need. Otherwise, you may find yourself with barter money or credit that you cannot use.
As Orlove noted, barter may occur in commercial economies, usually during periods of monetary crisis. During such a crisis, currency may be in short supply, or highly devalued through hyperinflation. In such cases, money ceases to be the universal medium of exchange or standard of value. Money may be in such short supply that it becomes an item of barter itself rather than the means of exchange. Barter may also occur when people cannot afford to keep money (as when hyperinflation quickly devalues it).
“Economic theory has always got to be historically bounded,” Beggs says. “I think it’s a mistake to think you’ll find the workings of modern money by going back to the origins of money.” He does point out that, while barter may not have been widespread, it’s possible that it happened somewhere and led to money, just given how much is unknown about such a large period of time.