An economic disaster involves either the widespread disruption or complete economic collapse at the national, regional, or global level. Economic history has been marked by cyclical fluctuations in the business cycle characterized by booms, panics, and busts. Less severe downturns result in economic crises and recessions, while more severe and prolonged downturns result in economic disasters and depressions. These crises can be cyclical, financial, or structural in nature. The 1930s global Great Depression was the worst economic disaster of modern history and led to significant changes in economic theory and government response to economic disasters.