Quantum mechanics - central not only to physics, but also to chemistry, materials science, and other fields - is notoriously abstract and difficult. Essential Quantum Mechanics is a uniquely concise and explanatory book that fills the gap between introductory and advanced courses, between popularizations and technical treatises. By focusing on the fundamental structure, concepts, and methods of quantum mechanics, this introductory yet sophisticated work emphasizes both physical and mathematical understanding. A modern perspective is adopted throughout - the goal, in part, being to gain entry into the world of 'real' quantum mechanics, as used by practicing scientists. With over 60 original problems, Essential Quantum Mechanics is suitable as either a text or a reference. It will be invaluable to physics students as well as chemists, electrical engineers, philosophers, and others whose work is impacted by quantum mechanics, or who simply wish to better understand this fascinating subject.