Letter of Credit
A written instrument from a bank or merchant in one location that requests that anyone or a specifically named party advance money or items on credit to the party holding or named in the document.
When a letter of credit is used, repayment of the debt is guaranteed by the bank or merchant issuing it. For example, if a bank is aware that a prominent citizen is trustworthy and can safely be relied upon to settle the debts which he or she incurs, then a letter of credit will be offered to that person on the basis of his or her good reputation so the person can travel without carrying large sums of money.
Letters of credit were used frequently before credit cards and travelers' checks were in common usage.