By introducing readers to relativistic quantum field theory, this class-tested textbook delivers a concise and modern course in quantum electrodynamics. Its self-contained nature is enhanced by detailed derivations and introductory materials on quantum mechanics and special relativity. This advanced undergraduate textbook employs the elementary concepts of the Schrödinger equation, Dirac notation, the harmonic oscillator and the hydrogen atom in a clear and up-to-date structure, organized around topics in waves, particles and interactions. The text includes many worked problems and examples, end-of-chapter exercises and summaries, as well as enrichment topics and boxed formulas, derivations and definitions. The author's extensive and award-winning research in lasers and quantum optics, coupled with more than 20 years of teaching experience with the course, well equipped him for this task.