the idea of bartering things is very old. a long time ago, people did not buy or sell with money. instead, they traded one thing for another to get what they wanted or needed. one person who owned many cows could trade with another person who had a lot of wheat. each would trade a little of what he had with the other. this would support the people on his farm. other things that were easier to carry around than cows also came to be held as valuable. this gave rise to trade items such as jewelry and spices.