Macroeconomics is the study of whole economies and economic aggregates such as national income, output, consumption, investment, and employment. It examines how these aggregates behave and interact at a national level, in contrast to microeconomics which focuses on individual decision-making units like households and businesses. Some key topics in macroeconomics include inflation, unemployment, economic growth, recessions, fiscal and monetary policy, and the effects of government intervention in the economy. Macroeconomics seeks to understand phenomena at a national or global scale using models that aggregate across individual economic actions.