Abstract
This chapter starts by defining economic inequality, deriving a Lorenz curve and then using it to calculate a Gini coefficient. It then presents data and trends on income and wealth inequality in the United States, showing that inequality has generally been increasing in recent decades. The third section considers international inequality data and trends, including global inequality. Seeming paradoxes are explained, including how global inequality is generally declining even as inequality in most countries is increasing. The final section discusses the causes of inequality in developed and developing countries, including the impact of policy choices, along with a summary of the relationship between inequality and economic growth.