In trade, barter (derived from baretor[1]) 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.[2] 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.

Anthropologists have argued, in contrast, "that when something resembling barter does occur in stateless societies it is almost always between strangers."[6] Barter occurred between strangers, not fellow villagers, and hence cannot be used to naturalistically explain the origin of money without the state. Since most people engaged in trade knew each other, exchange was fostered through the extension of credit.[7][8] Marcel Mauss, author of 'The Gift', argued that the first economic contracts were to not act in one's economic self-interest, and that before money, exchange was fostered through the processes of reciprocity and redistribution, not barter.[9] Everyday exchange relations in such societies are characterized by generalized reciprocity, or a non-calculative familial "communism" where each takes according to their needs, and gives as they have.[10]

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David Graeber argues that the inefficiency of barter in archaic society has been used by economists since Adam Smith to explain the emergence of money, the economy, and hence the discipline of economics itself.[2] "Economists of the contemporary orthodoxy... propose an evolutionary development of economies which places barter, as a 'natural' human characteristic, at the most primitive stage, to be superseded by monetary exchange as soon as people become aware of the latter's greater efficiency."[3] However, extensive investigation by anthropologists like Graeber has since then established that "No example of a barter economy, pure and simple, has ever been described, let alone the emergence from it of money; all available ethnography suggests that there never has been such a thing. But there are economies today which are nevertheless dominated by barter."[4]
Barter, the direct exchange of goods or services—without an intervening medium of exchange or money—either according to established rates of exchange or by bargaining. It is considered the oldest form of commerce. Barter is common among traditional societies, particularly in those communities with some developed form of market. Goods may be bartered within a group as well as between groups, although gift exchange probably accounts for most intragroup trade, particularly in small and relatively simple societies. Where barter and gift exchange coexist, the simple barter of ordinary household items or food is distinguished from ceremonial exchange (such as a potlatch), which serves purposes other than purely economic ones.
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).[15]