Based on a two-semester course held at the University of Heidelberg, Germany, this book provides an adequate resource for the lecturer and the student. The contents are primarily aimed at graduate students who wish to learn about the fundamental concepts behind constructing a Relativistic Quantum Theory of particles and fields. So it provides a comprehensive foundation for the extension to Quantum Chromodynamics and Weak Interactions, that are not included in this book. Contents: The Principles of Quantum Physics Lorentz Group and Hilbert Space Search for a Relativistic Wave Equation The Dirac Equation The Free Maxwell Field Quantum Mechanics of Dirac Particles Second Quantization Canonical Quantization Global Symmetries and Conservation Laws The Scattering Matrix Perturbation Theory Parametric Representation of a General Diagram Functional Methods Dyson–Schwinger Equation Regularization of Feynman Diagrams Renormalization Broken Scale Invariance and Callan–Symanzik Equation Renormalization Group Spontaneous Symmetry Breaking Effective Potentials