The richest 10% of Americans earn half of all of income. In Britain, the top 10% hold 40% of all the income. Inequality is not just an issue for rich countries. A billion people have been lifted out of poverty since 1990, and inequality has been rising in many other countries too. So, how much inequality is too much? Many may recoil from such a question - inequality is a dirty word. But this programme isn't about fairness. This programme is about economics – and how far inequality affects growth and prosperity. Presented by Linda Yueh. (Photo: A woman walks past a poor man. Credit: Getty Images)