Before the 1 of money, people used to get the goods and services they wanted by swapping things with others. The system was entirely 2 on an agreement between both people, each of whom needed to have what the other wanted to exchange.
The system of exchange started to work much more 3 with the introduction of money. By using precious metals which had been officially 4 and made into coins, it became possible to sell what you produced in 5 for coins, and then use the coins to buy anything you wanted from a third party.