Electron Paramagnetic Resonance is a comprehensive text on the field of electron paramagnetic resonance, covering both the theoretical background and the results of experiment. This book is composed of eight chapters that cover theoretical materials and experimental data on ionic crystals, since these are the materials that have been most extensively studied by the methods of paramagnetic resonance. The opening chapters provide an introduction to the basic principles of electron paramagnetic resonance and the methods of its measurement. The next chapters are devoted to the theory of spectra and experimental studies of ionic crystals, as well as the complexity of construction of a shape theory of a paramagnetic resonance line. The remaining chapters discuss the application of electron paramagnetic resonance technique to the study of metals, semiconductors, defects in crystals, and free radicals.