This book brings together tutorial-style expository chapters on both foundational material and current research areas in near-field optics. The starting point for the book was the Summer School at the 16th International Conference on Near-Field Optics, Nanophotonics and Related Techniques (2022), with each Summer School short course represented by a chapter, along with an additional specially selected chapter on a complementary topic. Together, the chapters within present a modern perspective of the area of near-field optics, focusing on recent theoretical approaches, but also capturing the evolution of the field. Each chapter is written by an internationally-recognized expert and provides a tutorial on a different aspects of the theory and analytical methods for near-field optics, nanophotonics, and plasmonics. While the material will be accessible at the graduate level, it will also provide a useful reference for established researchers in near-field optics and scientists in nearby fields.