Depression, a period in an industrial nation characterized by low production and sales and a high rate of business failures and unemployment. A depression is regarded as the lowest point in the business cycle. Extensive researches have been conducted on the causes of depressions. Most modern economic theories regard them as the outcome of a severe drop in demand, associated with falling investment and wages, both of which reduce consumption. Keynesianism is especially notable for its analysis of conditions which create and prolong depressions. Marxist economics, however, has consistently presented them as symptomatic of the crisis-ridden nature of capitalism. The most severe depression recorded is the Great Depression; but less severe depressions (or recessions) have occurred repeatedly in modern times, notably after the oil price shocks of 1973.