Monetary policy
Monetary policy include Central Bank or Government decision on the rate of interest, the money supply,exchange rate. A high interest rate reduce consumption and lower firm's investment. But a higher exchange rate will make exports more expensive and imports-cheaper. A rise of inerest rate reduce consumption, investment and export minus import (decrease AD).
Expansionary Monetary Policy increases the size of the money supply, or decreases the interest rate, they do it to reduce unemployment, but it may increase inflation

Contractionary Monetray Policy raise interest rate, to rduce inflation ( but again may increase unemployment.)Monetary policy can be use to control inflation, Inflation is defined to increases in price levels.Contractionary monetary policy has the effect of reducing inflation by reducing upward pressure on price levels.Contractionary fiscal policy use to control inflation, because it involves spending cuts and tax increases.