This book is designed as an introductory course in Quantum Field Theory (QFT) for students who have completed two full graduate-level courses in Quantum Mechanics (QM). Quantum Field Theory is the framework that combines quantum mechanics with special relativity, providing a comprehensive description of fundamental forces and particles. It is a crucial part of modern theoretical physics and essential for understanding the behaviour of elementary particles, the dynamics of fields, and the interactions that govern the universe at the smallest scales. This book is structured to gradually introduce the key concepts and mathematical tools necessary for mastering QFT. Each chapter builds on the knowledge acquired in previous sections, ensuring a coherent and comprehensive understanding of the subject. The material presented here helps doctoral students bridge the gap between the traditional quantum mechanics taught at the graduate level and the more advanced concepts and techniques used in quantum field theory. Key Features: Specifically designed to connect traditional quantum mechanics knowledge with quantum field theory. Presents a coherent learning path, including end-of-chapter trivia questions and problems, that gradually introduces the concepts and skills needed for grasping QFT. Tailored for doctoral-level physics students, ensuring appropriate depth and complexity. Travis Shane Taylor (born July 24, 1968) is an American scientist, engineer, science fiction writer, and the star of History Channel’s The Secret of Skinwalker Ranch, 2019 to present.