'Affine differential geometry' has undergone a period of revival and rapid progress in the past decade. This book is a self-contained and systematic account of affine differential geometry from a contemporary view. It covers not only the classical theory, but also introduces the modern developments of the past decade. The authors have concentrated on the significant features of the subject and their relationship and application to such areas as Riemannian, Euclidean, Lorentzian and projective differential geometry. In so doing, they also provide a modern introduction to the latter. Some of the important geometric surfaces considered are illustrated by computer graphics.