This chapter introduces macroeconomics and its key concepts. It discusses the roots of macroeconomics in the Great Depression and John Maynard Keynes' work. The chapter outlines the three main concerns of macroeconomics: inflation, output growth, and unemployment. It also describes the components of the macroeconomy including households, firms, government, and the rest of the world. Government policies like fiscal and monetary policy that impact the macroeconomy are introduced. Aggregate demand and supply and the methodology of using microeconomic foundations for macroeconomic analysis are summarized. Business cycles, expansion/contraction, and trends in the US economy since 1900 and 1970 are briefly outlined.