An unconditional written promise made by the buyer to the seller, signed by the buyer, to pay a sum of money to (or on behalf of) a named person on demand or on a specified or determinable date. The essential difference between a promissory note and a promissory note is that the promissory note is drawn by the buyer and sent to the seller, who receives payment. Both instruments primarily settle debts arising from international trade (they are legally enforceable).