Macroeconomics studies aggregate economic variables of an entire economy. It analyzes factors like national income, employment levels, inflation rates, and economic growth. Macroeconomics developed after John Maynard Keynes published his influential work on unemployment and effective demand. It examines unemployment, inflation, business cycles, economic growth, and international trade at the national level. Understanding macroeconomic trends is important for business decision-making because business environment is impacted by changes in macroeconomic variables and government policies.