This document provides a summary of key concepts in economics, including: 1) Firms produce goods and services while households consume them in the circular flow of economic activity. 2) Demand and supply determine market equilibrium price and quantity through interactions in product and input markets. 3) Consumer demand is influenced by price, income, wealth, tastes and expectations, while firm supply depends on price and costs. 4) Utility maximization theory explains that rational consumers seek to maximize satisfaction subject to their budget constraint.