Defined by the Bill of Exchange Act 1882 as an ‘unconditional promise in writing made by one person to another* signed by the maker, engaging to pay, on demand or at a fixed or determinable future time, a sum certain in money to, or to the order of, a specified person, or to bearer’. The note must be delivered to the payee or bearer. The person signing the note must pay it to a holder in due course; he has no right to deny the existence of the payee or the capacity of the payee to endorse. Notes payable on demand should be presented within a reasonable time – how long that is depends on the custom of the particular trade.
Reference: The Penguin Business Dictionary, 3rd edt.