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).
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In Spain (particularly the Catalonia region) there is a growing number of exchange markets. These barter markets or swap meets work without money. Participants bring things they do not need and exchange them for the unwanted goods of another participant. Swapping among three parties often helps satisfy tastes when trying to get around the rule that money is not allowed.
Barter-based economies are one of the earliest, predating monetary systems and even recorded history. People can successfully use barter in many almost any field. Informally, people often participate in barter and other reciprocal systems without really ever thinking about it as such -- for example, providing web design or tech support for a farmer or baker and receiving vegetables or baked goods in return. Strictly Internet-based exchanges are common as well, for example exchanging content creation for research.
In Canada, barter continues to thrive. The largest b2b barter exchange is Tradebank, founded in 1987. P2P bartering has seen a renaissance in major Canadian cities through Bunz - built as a network of Facebook groups that went on to become a stand-alone bartering based app in January 2016. Within the first year, Bunz accumulated over 75,000 users in over 200 cities worldwide.