From Chad Jones:
Since the early 2000s, research by Thomas Piketty, Emmanuel Saez, and their coathors has revolutionized our understanding of income and wealth in- equality. In this paper, I highlight some of the key empirical facts from this re- search and comment on how they relate to macroeconomics and to economic theory more generally. Top inequality is tightly linked to Pareto distributions. The paper describes simple mechanisms that give rise to this Pareto inequality and considers the economic forces that influence top inequality over time and across countries.