There are many kinds of bills of exchange, among which the most widely used is the import bill of exchange with letter of credit as the settlement method. Usually, the bank will pay the bill to the bank after the importer receives the bill and the importer confirms the bill. At this time, the bank gives credit to the enterprise according to the application of the importing enterprise and the enterprise's own credit status, and signs a draft agreement with the enterprise, stipulating that after the draft is due for repayment (the term is generally 30 days, 60 days, 90 days or 180 days), the bank will pay in advance instead of the importer, and the enterprise will take the documents. The bank's credit behavior is called draft, and the enterprise can get the documents without actual payment, as long as it is within the prescribed repayment period. Therefore, the popular point of negotiation can be understood as bank loans to enterprises, rather than enterprise advances. Since the enterprise borrows money from the bank, it must pay the corresponding interest to the bank, that is, bill interest.

In addition, there are other forms of negotiable instruments, which depend on different settlement methods and are essentially the same.