A A banknote (or ‘bill’ as it is often referred to in the US) is a type of negotiable promissory note, issued by a bank or other licensed authority, payable to the bearer on demand. that is stained with a special wash-resistant ink, triggered by an anti-theft mechanism located in a Money in physical form such as banknotes and coins. container or security case that is locked with a special seal and a security key. If the security case is stolen, any attempt to open it by force (or without using the correct key) will automatically trigger the mechanism and the banknotes will immediately become recognisable as stolen and should therefore be rejected at any financial institution. See Intelligent banknote neutralisation system.