The magnetism of nuclear spin systems has proved an amazingly fertile ground for the creativity of researchers. This happy circumstance results from the triple benediction that nature appears to have bestowed on nuclear spins: they are sporting spies-being infinitely manipulable (one is even tempted to say malleable), not unduly coy in revealing their secrets, and having a whole treasure house of secrets to reveal in the first place. researcher with Since spin dynamics are now orchestrated by the NMR ever more subtle scores, it is important to be able to tune into the pro­ ceedings with precision, if one is to make sense of it at all. Fortunately, it is not terribly difficult to do so, since in many ways spin dynamics are the theoretician's dream come true: they are often finite dimensional and quite tractable with basic quantum mechanics, frequently allowing near­ exact treatments and readily testable predictions. This book was conceived two years ago, with the objective of providing a simple, consistent introduction to the description of the spin dynamics that one encounters in modern NMR experiments. We believed it was a good time to attempt this, since it was possible by then to give sufficiently general descriptions of powelful classes of new NMR experiments. The choice of experiments we discuss in detail is necessarily subjective, al­ though we hope to have given a flavor of most of the important classes of pulse sequences, including some surface coil imaging applications.