A banknote (often known as a bill, paper money, or simply a note) is a type of negotiable instrument known as a promissory note, made by a bank, payable to the bearer on demand. Banknotes were originally issued by commercial banks, who were legally required to redeem the notes for legal tender (usually gold or silver coin) when presented to the chief cashier of the originating bank. These commercial banknotes only traded at face value in the market served by the issuing bank. Commercial banknotes have been replaced by national banknotes issued by central banks.