When two people each have items the other wants, both people can determine the values of the items and provide the amount that results in an optimal allocation of resources. Therefore, if an individual has 20 pounds of rice that he values at $10, he can exchange it with another individual who needs rice and who has something that the individual wants that's valued at $10. A person can also exchange an item for something that the individual does not need because there is a ready market to dispose of that item.
Throughout the 18th century, retailers began to abandon the prevailing system of bartering. Retailers operating out of the Palais complex in Paris, France were among the first in Europe to abandon the bartering, and adopt fixed-prices thereby sparing their clientele the hassle of bartering. The Palais retailers stocked luxury goods that appealed to the wealthy elite and upper middle classes. Stores were fitted with long glass exterior windows which allowed the emerging middle-classes to window shop and indulge in fantasies, even when they may not have been able to afford the high retail prices. Thus, the Palais-Royal became one of the first examples of a new style of shopping arcade, which adopted the trappings of a sophisticated, modern shopping complex and also changed pricing structures, for both the aristocracy and the middle classes.
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.