Particle Accelerator Physics I is designed to serve as an introduction to the field of high-energy particle accelerator physics and particle-beam dynamics. It covers the dynamics of relativistic particle beams, basics of particle guidance and focusing, lattice design, characteristics of beam transport systems and circular accelerators. Particle-beam optics is treated in the linear approximatin including sextupoles to correct for chromatic aberrations. Perturbations to linear beam dynamics are analysed in detail and correction measures are being discussed. Basic lattice design features and building blocks leading to the design of more complicated beam transport systems and circular accelerators are studied. Characteristics of synchrotron radiation and quantum effects due to the statistical emission of photons on particle trajectories are derived and applied to determine particle-beam parameters.