This book describes, as simply as is possible, the ideas and techniques of quantum field theory, on which is based our current understanding of subnuclear physics. In recent years this has advanced considerably with the discovery of charmed particles and the weak intermediate vector bosons predicted by gauge theories. After a brief survey of particle physics, the quantum theory of scalar and spinor fields, and then of gauge fields, is developed. The emphasis throughout is on functional methods, which have Played a large part in modern field theory. The book concludes with a brief survey of 'topological' objects in field theory. The author assumes a knowledge of quantum mechanics and special relativity.Ryder, Lewis H. is the author of 'Quantum Field Theory' with ISBN 9780521338592 and ISBN 052133859X.