This document summarizes key aspects of prices and the price system from an economics textbook. It discusses the role and benefits of the price system in guiding supply and demand, and its limitations such as externalities and public goods. Market equilibrium occurs when supply and demand are balanced. Surpluses and shortages cause prices to change to restore equilibrium. Shifts in supply or demand also shift the equilibrium point. Governments sometimes set prices to address market limitations or for strategic reasons, establishing price floors, ceilings, and rationing, but this interferes with market forces.