The issue of paper money in some cases grew out of the practice of debasing metal. However this may have been, governmental paper money may be looked upon as money for which a seigniorage of one hundred per cent is charged. The gain of seigniorage from paper money is greater and is just as easily secured as that from coinage of metals. Governmental paper money is called "political money," in contrast with commodity money. However, all coins that contain an element of seigniorage, or monopoly value, are to that degree "political money." The typical paper money is irredeemable; that is, it cannot be turned into bullion money on demand. It is simply put into circulation, usually with the "legal-tender" quality. Money has the _legal-tender_ quality (as the term is used in the United States) when, according to law, it must be accepted by citizens as a legal discharge for debts due them, unless otherwise provided in the contract. The prime purpose of making money legal tender is to reduce the danger of dispute as to payments; but another purpose often has been to force people to use a depreciated money whether they would or not. The purpose of the issue of political money is usually to gain the profit of seigniorage for the public treasury, and often it has been the desperate expedient of nearly bankrupt governments. Governmental paper money differs from bank notes in that its value does not necessarily depend on the promise of redemption by the issuer. It differs from promissory notes and bonds in that its value is not based on the interest it yields, but mainly on its monetary uses. The issue of paper money may save the government the payment of interest on an equal amount of bonds. The promise to receive paper in payment for taxes or for public lands may help to maintain its value by reducing its quantity, but nothing short of its prompt redemption in standard coins makes it truly redeemable.