Keynesian economics is a theory developed by John Maynard Keynes during the 1930s, primarily in response to the Great Depression. It emphasizes the role of government intervention in the economy, arguing that active fiscal policies, such as increased government spending and tax cuts, can help stimulate demand and pull an economy out of recession. According to Keynesian principles, during periods of economic downturn, consumer spending tends to decrease, leading to lower production and higher unemployment. By increasing public spending and investment, the government can boost demand, create jobs, and promote economic growth, ultimately stabilizing the economy.