This book addresses the needs of students struggling to understand the world of quantum mechanics. The authors attempt to find the optimal balance between comprehensiveness and clarity of presentation. This means offering a 'textbook with a human face'. It is abundant with equations, but also with thorough explanations and examples, which is precisely what is needed for its audience. The book also presents the most important new progress in the field: The quantum information theory and a new approach in our understanding and treatment of quantum systems ('Submissive quantum mechanics'), which enormously expands quantum intuition and opens up new avenues in technology. Relevant Course Codes: PH1700 - Quantum Mechanics PH1900 - Solid State Physics PH3100 - Condensed Matter Physics From Reviewers' Reports: "...I enthusiastically recommend publication of this book." Prof. V. Tsifrinovich, Polytechnic University, Brooklyn "...I strongly recommend publication of Dr. Fayngold's proposed textbook. I would be strongly inclined to use it as a personal reference as well as the textbook for an advanced undergraduate Quantum Mechanics course." Prof. L.A. Maljian, New Jersey Institute of Technology "...Overall I think the proposed book fills a real need and would be a worthwhile addition to existing texts." Prof. David Green, The New School University, New York