Monetary policy refers to how central banks use tools like interest rates, money supply, and credit conditions to achieve goals like price stability, economic growth, and unemployment control. The main tools are quantitative and qualitative credit controls. Quantitative controls directly target money supply through interest rates, open market operations, and reserve requirements. Qualitative controls influence credit allocation through margin requirements, credit rationing, and differential interest rates. Monetary policy can be expansionary by increasing money supply to boost economic activity, or contractionary by decreasing money supply to curb inflation.