Final answer:
In capitalist societies, the most common exchange among strangers is the market exchange. On foreign exchange markets, the U.S. dollar is the most traded currency, supported by exchanges at banks on the interbank market.
Step-by-step explanation:
The most common kind of exchange in contemporary capitalist societies is the market exchange. This is particularly true in transactions among strangers, where market exchange is the default setting. One can simply pay for goods or services required, facilitating a quick and unencumbered transaction. However, while market exchanges are efficient, they also encourage participants to operate out of self-interest and greed, rather than fostering cooperation and social well-being.
When referring to the foreign exchange markets, the most commonly traded currency is the U.S. dollar, followed by the euro, the British pound, the Australian dollar, and the Japanese yen. Individuals and firms usually engage in currency exchange through banks, which then trade the foreign exchange on the interbank market, connecting a wide network of banking entities and acting as dealers.