The RBI controls the money supply in the economy in various ways. The tools used by the Central bank to control the money supply can be quantitative or qualitative. Quantitative tools, control the extent of the money supply by changing the CRR, or bank rate or open market operations. Qualitative tools include persuasion by the Central bank in order to make commercial banks discourage or encourage lending which is done through moral suasion, margin requirement, etc. Hence, it is clear that the Margin requirement of loan is not a quantitative instrument for credit control by the Central Bank. Bank Rate- The RBI can influence money supply by changing the rate at which it gives loans to the commercial banks. This rate is called the Bank Rate in India. By increasing the bank rate, loans taken by commercial banks become more expensive; this reduces the reserves held by the commercial bank and hence decreases the money supply. A fall in the bank rate can increase the money supply. Another important tool by which the RBI also influences the money supply is Open Market Operations. Open Market Operations refers to the buying and selling of bonds issued by the Government in the open market. This purchase and sale is entrusted to the Central bank on behalf of the Government. When RBI buys a Government bond in the open market, it pays for it by giving a cheque. This cheque increases the total amount of reserves in the economy and thus increases the money supply. Selling of a bond by RBI (to private individuals or institutions) leads to a reduction in the quantity of reserves and hence the money supply. There are two types of open market operations: outright and repo. Outright open market operations are permanent in nature: when the central bank buys these securities (thus injecting money into the system), it is without any promise to sell them later. Similarly, when the central bank sells these securities (thus withdrawing money from the system), it is without any promise to buy them later. As a result, the injection/absorption of the money is of permanent nature. However, there is another type of operation in which when the central bank buys the security, this agreement of purchase also has specification about date and price of resale of this security. This type of agreement is called a repurchase agreement or repo. The interest rate at which the money is lent in this way is called the repo rate. Similarly, instead of an outright sale of securities the central bank may sell the securities through an agreement which has a specification about the date and price at which it will be repurchased. This type of agreement is called a reverse repurchase agreement or reverse repo. The rate at which the money is withdrawn in this manner is called the reverse repo rate. The Reserve Bank of India conducts repo and reverse repo operations at various maturities: overnight, 7-day, 14- day, etc. This type of operations have now become the main tool of monetary policy of the Reserve Bank of India.