The business cycle traces cyclical fluctuations in economic activity through Expansion (rising GDP and employment), Peak (maximum capacity utilization and overheating), Contraction (two consecutive quarters of negative real GDP constitute a recession), and Trough (the cycle bottom).
Monetary policy is conducted by the Federal Reserve to achieve its dual mandate of maximum employment and price stability. The Fed's most active tool is Open Market Operations (buying Treasuries injects bank reserves, lowering rates; selling Treasuries drains liquidity).
Fiscal policy encompasses federal spending and taxation. Keynesian economics advocates direct government spending and deficit stimulus during recessions to bolster aggregate demand, whereas Supply-side economics emphasizes tax reductions and deregulation to stimulate production and private investment.