Revised and updated, the first volume of this bestselling set provides an accessible and practical introduction to the first gauge theory included in the Standard Model of particle physics: quantum electrodynamics (QED). It includes a new chapter on Lorentz transformations and discrete symmetries in relativistic quantum mechanics. The authors also introduce Majorana fermions at an early stage, cover discrete symmetries in quantum field theory, and provide updates on nucleon structure functions and the status of QED.