This document discusses aggregate demand, aggregate supply, and equilibrium. It explains that aggregate demand is a downward sloping curve showing the quantity of output buyers will purchase at different price levels. Aggregate supply is an upward sloping curve showing the quantity firms will produce at different price levels. Equilibrium occurs where aggregate demand and supply intersect, determining output and price. The document outlines factors that shift these curves and cause inflation or recession. It also discusses how fiscal policy uses government spending and taxes to shift aggregate demand to stabilize the economy.