This book discusses the main concepts of the Standard Model of elementary particles in a compact and straightforward way. The theoretical results are derived using the physical phenomena as a starting point. This inductive approach allows a deep understanding of the methods used for solving problems in this field. This second, revised edition is expanded with biographical notes contextualizing the main results in quantum field theory. The series Texts and Monographs in Theoretical Physics collects advanced texts on selected topics from the broad and varied field of Theoretical Physics. The works in the series will enable the readers to get a deep understanding of current topics in Theoretical Physics, with a special emphasis on recent developments. They are aimed at advanced students and researchers in theoretical and mathematical physics, and can also serve as secondary reading for lectures and seminars at post-graduate levels.