This comeback stems from certain permanent features of our economies and their development. Modern economies are in constant change. Some changes are cyclical. Economic variables like GDP, housing prices and the volume of lending often increase strongly in upturns and decrease equally strongly in downturns. At times, economies are hit by booms. At other times, they are hit by downturns and recessions.
Economies are also subject to more fundamental, longer-term changes. In economic history, major changes in technology, population growth and economic systems have had sweeping effects on economic growth, the welfare of citizens and the birth and death of occupations and industries.