A promissory note
is a legal instrument (more particularly, a financial instrument), in which one party (the maker or issuer) promises in writing to pay a determinate sum of money to the other (the payee), either at a fixed or determinable future time or on demand of the payee, under specific terms. If the promissory note is unconditional and readily salable, it is called a negotiable instrument.
Referred to as a note payable in accounting (as distinguished from accounts payable), or commonly as just a "note", it is internationally defined by the Convention providing a uniform law for bills of exchange and promissory notes, although regional variations exist. A banknote is frequently referred to as a promissory note: a promissory note made by a bank and payable to bearer on demand. Mortgage notes are another prominent example.
Promissory notes are a common financial instrument in many jurisdictions, employed principally for short time financing of companies. Often, the seller or provider of a service is not paid upfront by the buyer (usually, another company), but within a period of time, the length of which has been agreed upon by both the seller and the buyer. The reasons for this may vary; historically, many companies used to balance their books and execute payments and debts at the end of each week or tax month; any product bought before that time would be paid only then. Depending on the jurisdiction, this deferred payment period can be regulated by law; in countries like France, Italy or Spain, it usually ranges between 30 to 90 days after the purchase.