Besides metals, many materials have been used for money. In some parts of the world men have used fishhooks, whale teeth, and elephant tails for money. Metal coins, of course, have always been popular as a medium of exchange. Because of their size and weight, coins are not suitable for all purposes.
Paper money is one solution.
Without paper money our life would be quite different. Paper money must be backed by a reliable source. People must have faith in their government. The Chinese printed the first paper money centuries ago. Marco Polo in the Thirteenth Century found paper money already in use in China.