Keynesian economics is a macroeconomic theory of total spending in the economy and its effects on output, employment, and inflation. It was developed by British economist John Maynard Keynes during the 1930s in an attempt to understand the Great Depression.

The central belief of Keynesian economics is that government intervention can stabilize the economy. Keynes’ theory was the first to sharply separate the study of economic behavior and individual incentives from the study of broad aggregate variables and constructs.