The term business cycle (or economic cycle or boom–bust cycle) refers to fluctuations in aggregate production, trade and activity over several months or years in a market economy.The business cycle is the upward and downward movements of levels of gross domestic product (GDP) and refers to the period of expansions and contractions in the level of economic activities (business fluctuations) around its long-term growth trend.These fluctuations occur around a long-term growth trend, and typically involve shifts over time between periods of relatively rapid economic growth (an expansion or boom), and periods of relative stagnation or decline (a contraction or recession).Business cycles are usually measured by considering the growth rate of real gross domestic product. Despite being termed cycles, these fluctuations in economic activity can prove unpredictable.