Expansion
When aggregate economic activity is increasing, the economy is said to be in an expansion. This refers to a period of economic growth, characterized by an increase in output, income, employment, and overall economic activity.

Characteristics of an Expansion
During an expansion, several key indicators of economic health are on the rise:

1. Gross Domestic Product (GDP) Growth: GDP, which measures the total value of goods and services produced in an economy, typically experiences positive growth during an expansion. This indicates that the overall output of the economy is increasing.

2. Increased Consumer Spending: As economic conditions improve, consumers tend to spend more on goods and services, leading to increased sales and business activity.

3. Low Unemployment: Expansions are usually accompanied by a decrease in unemployment rates as businesses expand their operations and hire more workers to meet growing demand.

4. Rising Stock Market: During an expansion, stock prices tend to increase as companies generate higher profits and investors become more optimistic about future economic prospects.

5. Improved Business Confidence: As the economy expands, businesses typically become more confident about their prospects and may invest in new projects, expand production capacities, or hire additional employees.

6. Increasing Real Estate Prices: Expansions often lead to rising real estate prices as demand for housing and commercial properties increases.

Causes of an Expansion
Expansions are typically driven by a combination of factors, including:

1. Increased Aggregate Demand: When consumers and businesses have more income and confidence, they tend to spend more, leading to an increase in aggregate demand.

2. Monetary Policy: Expansionary monetary policies, such as lowering interest rates or increasing the money supply, can stimulate borrowing and spending, leading to economic growth.

3. Fiscal Policy: Government measures, such as tax cuts or increased government spending, can also boost economic activity during an expansion.

4. Technological Advancements: Innovation and technological advancements can drive economic growth by increasing productivity, creating new industries, and improving efficiency.

Conclusion
In conclusion, an expansion refers to a period of economic growth characterized by increasing aggregate economic activity. During an expansion, key indicators such as GDP, consumer spending, employment, stock market prices, business confidence, and real estate prices are typically on the rise. Expansions are typically caused by increased aggregate demand, expansionary monetary and fiscal policies, and technological advancements.