non profit times jobs Why? Interest rate, in the form of expression, refers to the ratio of the amount of interest to the total amount of borrowed capital in a certain period of time.  the interest rate is the interest level per unit time of the unit currency, indicating the interest rate. Economists have been looking for a theory that can fully explain the structure and change of interest rates. Interest rates are usually controlled by the central bank of the country and administered by the federal reserve board in the United States. Today, interest rates are one of the important tools for macroeconomic regulation. The determination of this ratio mainly depends on the supply and demand relationship between the two sides and the competition. In general, the interest rate falls when the supply exceeds demand. Interest rates rise when demand exceeds supply. In addition, law, habit and so on also have a larger role. Marx's theory is of guiding significance to explain the question of interest rate decision under socialized production. Interest rates in different countries have different connotations. In China, interest rates typically refer to bank interest rates, further pointing to the pboc's benchmark deposit and lending rates. In the United States, mainly refers to the bond market interest rates, the fed adjustment of benchmark interest rate, also not have mandatory administrative benchmark interest rates, but through open market operations after determine its rate for overnight loans between Banks. Any transaction can be seen as a contract between the two parties. The so-called transaction cost can be seen as the cost of the transaction contract. According to Mr Coase and others, a type of transaction costs arise from the accidental factors that occur when a deal is signed. These incidental factors may not be written into the contract due to the fact that they could not be foreseen in advance, or although they could be foreseen, they could not be written into the contract due to too many factors. Another type of transaction costs is the signing of contracts and the cost of monitoring and enforcing contracts.