Available for the first time in paperback, String Theory comprises two volumes which give an up-to-date, comprehensive and pedagogic account of the subject. Volume 1, An Introduction to the Bosonic String, gives a thorough introduction to the bosonic string, based on the Polyakov path integral and conformal field theory. Volume 2, Superstring Theory and Beyond, begins with an introduction to supersymmetric string theories and goes on to a broad presentation...