The most primitive way of exchange should be the barter trade. In this form of transaction, people used goods to exchange for the things that they had in mind. For instance, if person A wanted a book and he had a spare goat, he must look for someone who had the exact opposite, that is, that someone, say person B, must have a spare book of person A's choice and is also in need of a goat. Having found such a person, the problem does not end here. A big goat may worth not only one book, hence person B may have to offer person A something else, say five chickens. However, he runs the risk of person A rejecting the offer as he may not need the chickens. The above example clearly illustrates the inefficiency of barter trading.