Quantum field theory (QFT) is a theoretical approach to the study of subatomic particles and quasiparticles integrating classical field theory, quantum mechanics and the theory of special relativity. In QFT, particles are treated as excited states or quanta of their fields. Interactions between these particles are described by the interaction terms in the corresponding Lagrangian and through the Feynman diagrams. The concepts of path integral formulation, canonical quantization, renormalization, gauge theory, supersymmetry, etc. are integral to the development of quantum field theory. This book provides comprehensive insights into the field of quantum field theory. It unfolds the innovative aspects of this discipline, which will be crucial for the progress of this field in the future. It will serve as a valuable source of reference for graduate and post graduate students as well as experts.