Interest rate is also called interest rate. Represents the ratio of interest to principal in a certain period, usually expressed as a percentage, which is called annual interest rate. Its calculation formula is: interest rate = interest amount/principal interest rate, which determines the interest amount obtained by a certain amount of loan capital in a certain period. The factors that affect interest rates are mainly the marginal productivity of capital or the relationship between supply and demand of capital. In addition, there is the length of time promised to send money and the degree of risk taken. Interest rate policy is the main means of western macro-monetary policy. * In order to intervene in the economy, we can indirectly adjust the currency by changing interest rates. During the depression, lower interest rates, expand money supply and stimulate economic development. In the period of inflation, we should raise interest rates, reduce the money supply and curb the vicious development of the economy. Classify interest rate types according to different classification methods and angles, so as to show the characteristics of different interest rate types more clearly. According to the term unit of interest rate calculation, it can be divided into: annual interest rate, monthly interest rate and daily interest rate; According to the determination of interest rate, it can be divided into official interest rate, public interest rate and market interest rate; According to whether the interest rate fluctuates during the loan period, it can be divided into fixed interest rate and floating interest rate; According to the status of interest rate, it can be divided into: benchmark interest rate and general interest rate; According to the duration of credit behavior, it can be divided into: long-term interest rate and short-term interest rate; According to the real level of interest rate, it can be divided into: nominal interest rate and real interest rate; According to different borrowers, it is divided into: central bank interest rates, including rediscount and refinancing rates; Commercial bank interest rates, including deposit interest rate, loan interest rate, discount rate, etc. ; Non-bank interest rates, including bond interest rates, corporate interest rates and financial interest rates; According to whether it is preferential, it can be divided into general interest rate and preferential interest rate. Various classifications of interest rates cross each other. For example, the three-year resident savings deposit interest rate is 4.95%, which is not only the annual interest rate, but also the fixed interest rate, differential interest rate, long-term interest rate and nominal interest rate. All kinds of interest rates are interrelated and internally related, and they maintain a relative structure, thus forming an organic whole, thus forming a national interest rate system. Interest rate determination theory Marx's interest rate determination theory is based on an accurate grasp of the source and essence of interest. Marx revealed that interest is a part of the surplus value separated by the capitalist who lends capital from the capitalist who borrows capital, and profit is the transformation form of surplus value. This qualitative stipulation of interest determines its quantitative stipulation (this qualitative stipulation of interest determines its quantitative stipulation), the amount of interest depends on the total profit, and the interest rate depends on the average profit rate. Marx further pointed out that between the average profit rate and zero, the interest rate depends on two factors: first, the profit rate; The second is the proportion of total profits distributed between borrowers and lenders. The determination of this ratio mainly depends on the relationship between supply and demand and the degree of competition between borrowers and lenders. Generally speaking, when supply exceeds demand, interest rates fall; When demand exceeds supply, interest rates will rise. In addition, laws and customs also play a greater role. Marx's theory has guiding significance for explaining the interest rate decision under the condition of socialized mass production. Western interest rate determinism mostly focuses on the analysis of the relationship between supply and demand, and holds that interest rate is a kind of price. The difference lies in what kind of supply and demand determines the interest rate. For example, Marshall's real interest rate theory emphasizes the role of non-monetary real factors-productivity and economy in interest rate determination. Productivity is expressed by marginal propensity to invest, and savings is expressed by marginal propensity to save. Investment is a decreasing function of interest rate, and savings is a decreasing function of interest rate. The change of interest rate depends on the equilibrium point of investment and savings. Keynes's theory of money supply and demand holds that interest rates are determined by monetary factors rather than practical factors. Money supply is an exogenous variable determined by the central bank, and money demand depends on people's liquidity preference. When people's liquidity preference increases, they tend to increase the amount of money they hold, so the interest rate is determined by the money demand and money supply determined by liquidity preference. The theory of loanable funds integrates the first two kinds of interest rate determinism, and holds that interest rate is determined by supply and demand in loanable funds. Supply includes total savings and new money from banks, while demand includes total investment and new money. The decision of interest rate depends on the * * * equilibrium of commodity market and money market.