Mainstream macroeconomic theory is a direct outgrowth of the work of the British economist John Maynard Keynes. Macroeconomics is the study of the economy as a whole. Macroeconomic concepts define specific aggregate phenomena in the economy. When macroeconomic concepts are defined to be quantitatively variable phenomena, we refer to those concepts as macroeconomic variables. Macroeconomic theories are primarily attempts to logically explain the interrelationships between macroeconomic variables and the dynamics by which such variables change.
Macroeconomic theories provide a basis for macroeconomic policy.
Macroeconomic policy may be formulated toward the objective of supporting higher economic growth and lower unemployment, to moderate economic growth and inflation, to stimulate export growth, or a wide range of other possible objectives. Political debates are often waged over the terrain of present and future macroeconomic policies. In many economies, including the United States, non-elected officials play important and often critical roles in determining macroeconomic policies. The Board of Governors of the Federal Reserve System plays such a role in the United States. Introduction to Macroeconomics attempts to explain the role of such institutions in shaping macroeconomic policies.