A banknote (informally note in British English and bill in American English; also called paper money) is a written assurance of payment to the holder of the note on demand, i.e. a 'promissory note'. Notes are issued by banks, such as the Bank of England, and along with coins and other forms of money, are effectively used as a more convenient way of exchange and bartering.
The designs of banknotes vary according to the place where they are used and their face value. Bank of England banknotes, for instance, are used in the United Kingdom and come in denominations of £5, £10, £20 and £50, each a different size and colour, which allows easy recognition. Banknotes often feature designs of people or places of cultural significance: the U.S. $1 bill, for example, bears the image of George Washington.
Modern banknotes typically incorporate increasingly sophisticated anti-counterfeiting measures, such as patterns which only appear when held up to ordinary or ultraviolet light. Many banks issue new designs every few years in an effort to thwart illegal duplication of banknotes.