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.
Modern barter and trade has evolved considerably to become an effective method of increasing sales, conserving cash, moving inventory, and making use of excess production capacity for businesses around the world. Businesses in a barter earn trade credits (instead of cash) that are deposited into their account. They then have the ability to purchase goods and services from other members utilizing their trade credits – they are not obligated to purchase from those whom they sold to, and vice versa. The exchange plays an important role because they provide the record-keeping, brokering expertise and monthly statements to each member. Commercial exchanges make money by charging a commission on each transaction either all on the buy side, all on the sell side, or a combination of both. Transaction fees typically run between 8 and 15%.
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).
Since the latest series of worldwide economic meltdowns, people have bartered in growing numbers. Last year, the 100 members of the International Reciprocal Trade Association, a network of barter and trade exchanges, facilitated the bartering of billions of dollars’ worth of goods and services around the world. (The IRTA uses its own barter currency called Universal Currency.) In some areas of Greece, bartering has become as second nature as paying for things with cash—there’s even a new barter-style currency called the TEM, accrued through offering goods and services via a vast online network and regular open-air market days. Spain’s time bank system, in which people exchange hours of labour instead of units of currency, has grown exponentially as a result of the country’s crippled economy.