Banks as financial intermediaries between ultimate savers and borrowers,[12] and their ability to generate a medium of exchange marked higher than a fiat currency's store of value, is the basis of banking. Central banking is based on the principle that no medium requires more than the guarantee of the state that it can be redeemed for payment of debt as "legal tender" – so all money equally backed by the state is considered good money, within that state.[dubious ] So long as that state produces anything of value to others, the medium of exchange has some value, and the currency may also be useful as a standard of deferred payment among others.