Modern experimental developments in condensed matter & ultracold atom physics present formidable challenges to theorists This book provides a pedagogical introduction to quantum field theory in many-particle physics emphasizing the applicability of the formalism to concrete problems This second edition contains two new chapters developing path integral approaches to classical & quantum nonequilibrium phenomena Other chapters cover a range of topics from the introduction of many-body techniques & functional integration to renormalization group methods the theory of response functions & topology Conceptual aspects & formal methodology are emphasized but the discussion focuses on practical experimental applications drawn largely from condensed matter physics & neighboring fields Extended & challenging problems with fully worked solutions provide a bridge between formal manipulations & research-oriented thinking Aimed at elevating graduate students to a level where they can engage in independent research this book complements graduate level courses on many-particle theory