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.
Other countries, though, do not have the reporting requirement that the U.S. does concerning proceeds from barter transactions, but taxation is handled the same way as a cash transaction. If one barters for a profit, one pays the appropriate tax; if one generates a loss in the transaction, they have a loss. Bartering for business is also taxed accordingly as business income or business expense. Many barter exchanges require that one register as a business.
Consumer-based barter systems aren’t the only trade in town, either. In the GTA, there is a robust business-to-business barter system, similar to wir but on a smaller scale. Businesses sign up for a service—there are several available—and trade unbilled work hours or dust-covered inventory for goods and services they couldn’t otherwise afford, especially during recessionary times: often things that attract top talent and retain big clients, such as advertising, promotional gear or client perks.