Final answer:
An expansion occurs when potential output grows rapidly, when actual output rises above potential output, or when both of these occur.
Step-by-step explanation:
In economics, an expansion occurs when potential output grows rapidly, when actual output rises above potential output, or when both of these occur.
An expansion represents a period of economic growth, where potential output increases due to factors like investment in physical and human capital, technology advancements, and catch-up growth.
An increase in actual output above potential output indicates that the economy is performing better than its full employment level, which can be a result of increased demand or productivity.