Over the last two decades mass spectrometry has become one of the central techniques in analytical chemistry to indentify unknown substances and to verify the quality of manufactured substances such as drugs. This book provides a "teach-yourself" approach to understanding how to interpret the spectra produced from a mass spectrometer, allowing the reader to master the subject by solving problems. It features comprehensive coverage based on real spectra using MS of different compounds to illustrate the dependence of MS fragments on the structure, ultimately enabling the reader to rapidly identify unknown substances.