Polymer banknotes are banknotes made from a synthetic polymer such as biaxially oriented polypropylene (BOPP). Such notes incorporate many security features not available in paper banknotes, including the use of metameric inks. Polymer banknotes last significantly longer than paper notes, causing a decrease in environmental impact and a reduced cost of production and replacement. Modern polymer banknotes were first developed by the Reserve Bank of Australia (RBA), Commonwealth Scientific and Industrial Research Organisation (CSIRO) and The University of Melbourne. They were first issued as currency in Australia during 1988 ; by 1996, the Australian dollar was switched completely to polymer banknotes. Romania was the first country in Europe to issue a plastic note in 1999 and became the third country after Australia and New Zealand to fully convert to polymer by 2003.

A banknote—also called a bill, paper money, or simply a note—is a type of negotiable promissory note, made by a bank or other licensed authority, payable to the bearer on demand. Banknotes were originally issued by commercial banks, which were legally required to redeem the notes for legal tender 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 Commercial banknotes have primarily been replaced by national banknotes issued by central banks or monetary authorities.