Ans: A certificate or a token that can be exchanged for commodities is called representative money. For example, you might have gold which you keep in a bank vault and carry a paper certificate to denote the value of the gold you have in the bank. This certificate is good to be redeemed for gold at any time. A certificate is also a safer and easier way to carry your actual gold asset. People, over time, have come to trust the paper certificate as much as they trust gold. Representative money is what gave way to fiat-money, which is used in modern economies of today.