Feudalism was a system of political and economic organization that dominated Europe in the Middle Ages. It was based on the relationship between lords and vassals, in which lords granted land to vassals in exchange for military service and other obligations.

Mercantilism was an economic system that emerged in Europe in the 16th century. It was based on the belief that a country's wealth and power could be increased by accumulating gold and silver.

Capitalism is an economic system that emerged in Europe in the 18th century. It is based on the private ownership of the means of production and the pursuit of profit.

Socialism is an economic system that emerged in the Soviet Union in the 1920s. It is based on the public ownership of the means of production and the distribution of goods and services according to need.

Communism is an economic system that emerged in China in the 1940s. It is based on the public ownership of the means of production and the distribution of goods and services according to need.

The Great Depression was an economic crisis that occurred in the United States in the 1930s. It was the longest and most severe economic downturn in American history.

The New Deal was an economic policy that was implemented by President Franklin D. Roosevelt in response to the Great Depression. It consisted of a series of programs and reforms designed to stimulate the economy and provide relief to the unemployed.

The Great Society was an economic policy that was implemented by President Lyndon B. Johnson in the 1960s. It consisted of a series of programs and reforms designed to address poverty, education, healthcare, and other social issues.

The Great Recession was an economic crisis that occurred in the United States in the 2008. It was the longest and most severe economic downturn since the Great Depression.

The American Recovery and Reinvestment Act was an economic policy that was implemented by President Barack Obama in response to the Great Recession. It consisted of a series of programs and reforms designed to stimulate the economy and provide relief to the unemployed.

Capitalism is the current economic system in the United States. It is based on the private ownership of the means of production and the pursuit of profit.

The three main factors of production are land, labor, and capital. Land is the natural resources that are used to produce goods and services. Labor is the human effort that is used to produce goods and services. Capital is the physical assets that are used to produce goods and services.

A microeconomic model focuses on individual markets, while a macroeconomic model focuses on the economy as a whole. Microeconomic models are used to analyze the behavior of individual consumers and firms, while macroeconomic models are used to analyze the behavior of the government and the central bank.

A positive economic statement describes what is, while a normative economic statement describes what should be. Positive economic statements are based on facts, while normative economic statements are based on values. Positive economic statements can be tested, while normative economic statements cannot be tested.

A stock variable is a measure of the amount of something at a point in time, while a flow variable is a measure of the rate of change of a stock variable. For example, the stock of money in the economy is a measure of the total amount of money in the economy at a point in time, while the flow of money in the economy is a measure of the rate at which money is being created or destroyed.