EPR spectroscopy is a versatile, nondestructive technique widely used in chemistry, biology, and physics. It detects molecules and materials with unpaired electrons making it a very selective technique that produces a wealth of information on such systems. Its high sensitivity makes it suitable in analyzing very small samples, single crystals, or reaction intermediates like radicals. This textbook takes a practical approach that introduces the basic concepts of EPR to sufficient detail to allow the reader to gain a basic knowledge of EPR and understand how experiments are carried out and how spectra are analyzed and interpreted. Many illustrative examples are included drawn from solid-state physics and bioinorganic chemistry. It is suitable as a short introduction for advanced undergraduate and beginning graduate students taking their first steps into EPR research.