It is divided into short-term financial instruments and long-term financial instruments according to term, direct financial instruments and indirect financial instruments according to financing forms, creditor's rights financial instruments and ownership financial instruments according to rights and obligations, and primary financial instruments and derivative financial instruments according to whether direct credit activities are related or not.

Financial instruments are also called "credit instruments" or "trading instruments". When a department with insufficient funds borrows funds from a department with sufficient funds, or an issuer raises funds from investors, it is a written document with a certain format, which stipulates the obligations of the debtor and the rights of creditors. This is a legally binding contract.

Financial instruments are the objects of financial market transactions, which are produced and developed with the development of credit relations. In modern complex financial relations, what is agreed verbally is impossible.