Statistical studies are hardly needed to prove the existence of immense material inequality between human beings. It is evident to anyone who walks down the street in most major cities or watches a television newscast which jumps from images of famine in Angola to the business or the football transfer news. This article takes the existence of great inequality as given but discusses the various ways in which that inequality can be and is measured and surveys evidence about how inequality on a world scale has evolved during the last century and especially since 1980.
