The technique of nuclear magnetic resonance (NMR) spectroscopy is an important tool in biochemistry and biophysics for the understanding of the structure and, ultimately, the function of biomolecules. This textbook explains the salient features of biological NMR spectroscopy to undergraduates and postgraduates taking courses in NMR, 4iological NMR, physical biochemistry, and biophysics. Unlike other books in the general field of NMR (except the advanced treatises), the approach here is to introduce and make use of quantum mechanical product operators as well as the classical vector method of explaining the bewildering array of pulse sequences available today. The book covers two-dimensional, three-dimensional, and four-dimensional NMR, and their application to protein and DNA structure determination. A unique feature is the coverage of the biological aspects of solid-state NMR spectroscopy. The author provides many selected examples from the research literature, illustrating the applications of NMR spectroscopy to biological proteins.