"Commercial bank" is a free translation of English commercial bank. On the issue of defining this concept, Chinese and western formulations are different. We believe that the definition of commercial banks should include the following points: first, commercial banks are intermediaries that issue and accept credit; Second, commercial banks are enterprises whose purpose is to obtain profits; Third, commercial banks are the only financial organizations that can provide "bank currency" (demand deposits). Generally speaking, the concept of commercial banks can be understood as follows: commercial banks are money-operated enterprises whose main business is industrial and commercial deposits and loans, and whose purpose is to obtain profits. This definition method is actually a generalization of the definition of commercial banks by Chinese and western scholars.

Investment banks are non-bank financial institutions mainly engaged in securities issuance, underwriting, trading, enterprise restructuring, mergers and acquisitions, investment analysis, venture capital, project financing and other businesses, and are the main financial intermediaries in the capital market.

Investment bank is the product of the development of securities and joint-stock company system at a specific stage, and it is an important subject of developed securities market and mature financial system. In the development of modern social economy, it plays an important role in communicating the supply and demand of funds, building a securities market, promoting enterprise mergers and acquisitions, promoting industrial concentration and economies of scale, and optimizing resource allocation.

An institution established by the government, responsible for controlling the national money supply and credit situation, and supervising the financial system, especially commercial banks and other savings institutions.

The central bank is the highest monetary and financial management institution in a country and occupies a dominant position in the financial systems of various countries. The functions of the central bank are macro-control, financial security and stability, and financial services.

The central bank is a "currency issuing bank", which plays an important role in regulating the money supply and stabilizing the currency value. The central bank is the "bank of the bank", which keeps the bank's reserves in a centralized way and provides loans to the bank as the "lender of last resort".

The central bank is a "national bank", it is the maker and executor of the national monetary policy, and it is also a tool for the government to intervene in the economy; At the same time, it provides financial services for the country, acts as an agent for the national treasury, issues treasury bonds and raises funds for the government; Participate in international financial organizations and various international financial activities on behalf of the government.

The fundamental difference between the business of the central bank and the business of other financial institutions is that the business of the central bank is not for profit, but for achieving the national macroeconomic goals, which is determined by the status and nature of the central bank.

The main business of the central bank includes: currency issuance, centralized deposit reserve, loans, rediscount, securities, gold and foreign exchange, and fund transfer and liquidation and fund allocation for commercial banks and other financial institutions.