Reason for recession is widespread decline in the GDP and employment and trade lasting from six months to a year.
In economics, the term recession generally describes the reduction of a country's gross domestic product (GDP) for at least two quarters. The usual dictionary definition is "a period of reduced economic activity", a business cycle contraction.
The United States-based National Bureau of Economic Research (NBER) defines economic recession as: "a significant decline in economic activity spread across the economy, lasting more than a few months, normally visible in real GDP growth, real personal income, employment (non-farm payrolls), industrial production, and wholesale-retail sales.
Your vote on this answer has already been received
Well there r many......actully most of the worlds economy depends on USA and recession in US has cost it in the whole world....wasting money by US in war preparations against iraq, afganistan..pakistan....loose in industries...declining export....this r major reasons for market slow down in US which affected the world