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).
When barter has appeared, it wasn’t as part of a purely barter economy, and money didn’t emerge from it—rather, it emerged from money. After Rome fell, for instance, Europeans used barter as a substitute for the Roman currency people had gotten used to. “In most of the cases we know about, [barter] takes place between people who are familiar with the use of money, but for one reason or another, don’t have a lot of it around,” explains David Graeber, an anthropology professor at the London School of Economics.
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.
Bartering is the process of obtaining goods or services by direct exchange without the use of currency. In times of economic instability or currency devaluation, it can be a great way to ensure the flow of necessary items and services into your household without using precious funds. Historically, face-to-face exchanges between familiar parties were most common, but the Internet has opened up a new medium for bartering opportunities for both person-to-person exchanges and third-party facilitated transactions.
In his analysis of barter between coastal and inland villages in the Trobriand Islands, Keith Hart highlighted the difference between highly ceremonial gift exchange between community leaders, and the barter that occurs between individual households. The haggling that takes place between strangers is possible because of the larger temporary political order established by the gift exchanges of leaders. From this he concludes that barter is "an atomized interaction predicated upon the presence of society" (i.e. that social order established by gift exchange), and not typical between complete strangers.