Although originally invented and employed by physicists, electron paramagnetic resonance (EPR) spectroscopy has proven to be a very efficient technique for studying a wide range of phenomena in many fields, such as chemistry, biochemistry, geology, archaeology, medicine, biotechnology, and environmental sciences. Acknowledging that not all studies require the same level of understanding of this technique, this book thus provides a practical treatise clearly oriented toward applications, which should be useful to students and researchers of various levels and disciplines. In this book, the principles of continuous wave EPR spectroscopy are progressively, but rigorously, introduced, with emphasis on interpretation of the collected spectra. Each chapter is followed by a section highlighting important points for applications, together with exercises solved at the end of the book. A glossary defines the main terms used in the book, and particular topics, whose knowledge is not required for understanding the main text, are developed in appendices for more inquisitive readers.