This book offers a comprehensive introduction to modern macroeconomic theory, bridging foundational concepts with contemporary applications. It begins by exploring the core macroeconomic model featuring rational agents and competitive markets—the cornerstone for analyzing business cycles, economic growth, and asset pricing. From there, it transitions to more complex frameworks, including models that incorporate market imperfections and strategic interactions, crucial for understanding liquidity challenges and financial crises. Designed as a primer, this text explains the theoretical foundations of modern macroeconomics in an accessible way, without relying on advanced recursive techniques.