Unlike commodity money, such as gold coins or paper notes, which can be exchanged for precious metals, fiat money is fully backed by faith and trust in the government that issued it. This makes sense because governments require people to pay taxes in the paper money they issue. Since everyone has to pay taxes, people will accept the fiat money in return. Other theories of money, such as credit theory, suggest that since all money is a loan-debt relationship, it doesn't matter if the money is backed by something to maintain value or not.