[1][2] The explanation of fluctuations in aggregate economic activity between expansions and contractions ("booms" and "busts" within the "business cycle") is one of the primary concerns of macroeconomics.
[3] According to the four stages of a business cycle (expansion, peak, contraction, trough), an expansion is an upward trend when a country's economy experiences relatively rapid growth as measured by a rise in industrial production, employment, consumer spending, and utilization of resources.
[4][5] Whereas a recession is defined as two consecutive quarters of decline in GDP,[6] economic recovery and prosperity are two successive phases of expansion.
[4] From a microeconomic standpoint, expansion usually means enlarging the scale of a single company or firm.
This can be achieved through internal actions—opening branches, finding new customers, inventing products, developing lines of business—and through integration, for example, taking over or merging with other companies.