Ergodic theory grew out of an important problem of statistical mechanics which was resolved by Birkhoff and von Neumann in the 1930s. Since that time the subject has made its way to the centre of pure mathematics, drawing on the techniques of many other areas and, in turn, influencing those areas. The author has provided in this slim volume a speedy introduction to a considerable number of topics and examples. He includes sections on the classical ergodic theorems, topological dynamics, uniform distribution, Martingales, information theory and entropy. There is a chapter on mixing and one on special examples. The book concludes with an appendix on the spectral multiplicity theory of unitary operators.