US household income has grown significantly, but much of that growth seems to be at the very top of the distribution. Just how much inequality has increased and why it is growing is a topic of debate among economists. Part of the challenge lies in a seemingly basic question: what exactly counts as income?

In a paper in the Journal of Economic Perspectives, author Matthieu Gomez disentangles the notions of income that economists frequently use and helps pinpoint what's really behind the rise in inequality.

Gomez recently spoke with Tyler Smith about defining income, recent patterns in income inequality, and the best tools for reducing inequality.