This document provides definitions and explanations of key economic concepts. It begins by defining microeconomics and macroeconomics. Microeconomics examines individual economic decisions and interactions, while macroeconomics looks at aggregate economic performance and structure at a national or international level. The document then discusses various market structures like perfect competition, monopoly, oligopoly, and their characteristics. It also covers concepts like demand, supply, equilibrium, elasticity, costs of production, and opportunity cost. The final sections define additional economic terms and concepts related to welfare economics, labor economics, and measures like unemployment rate.