The CRR and SLR are tools used by the Reserve Bank of India to control liquidity in the banking system. The CRR requires scheduled commercial banks to hold a certain percentage of their total demand and time liabilities as deposits with the RBI. This minimum ratio is determined by the RBI and allows them to drain or inject liquidity into the system by adjusting the ratio up or down. The SLR requires banks to invest a certain percentage of their net demand and time liabilities in approved securities, thus affecting how much banks can lend out.