A well written, readable and easily accessible introduction to "Choquet
theory", which treats the representation of elements of a compact convex
set as integral averages over extreme points of the set. The interest in
this material arises both from its appealing geometrical nature as well
as its extraordinarily wide range of application to areas ranging from
approximation theory to ergodic theory. Many of these applications are
treated in this book. This second edition is an expanded and updated
version of what has become a classic basic reference in the subject.