Reviews of the Second Edition This book is well written and very readable The book is a self consistent introduction to the path integral formalism and no prior knowledge of it is required, although the reader should be familiar with quantum mechanics This book is an excellent guide for the reader who wants a good and detailed introduction to the path integral and most of its important application in physics I especially recommend it for graduate students in theoretical physics and for researchers who want to be introduced to the powerful path integral methods Mathematical Reviews this volume gives a clear and neat account by way of practical use Accordingly, it will be a useful compact textbook for graduate students to learn quantum field theory by path integral approach, especially, to get quickly an overview of its technical side so as to know the applicability of its methods to various areas Zentralblatt MATH This unique book describes quantum field theory completely within the context of path integrals With its utility in a variety of fields in physics, the subject matter is primarily developed within the context of quantum mechanics before going into specialized areas All the existing chapters of the previous edition have been expanded for clarity The chapter on anomalies and the Schwinger model has been completely rewritten for better logical clarity Two new chapters have been added at the request of students and faculty worldwide The first describes Schwinger s proper time method with simple examples both at zero and at finite temperature while the second develops the idea of zeta function regularization with simple examples This latest edition is a comprehensive and much expanded version of the original text