This book introduces the basic concepts of quantum information, including the mathematical foundations of linear algebra and information theory required for quantum information, single-particle quantum systems, general descriptions of quantum systems, applications in multi-particle quantum systems, and the basics of quantum information theory. The book is intended for readers with mathematical backgrounds in linear algebra, probability theory, etc., aiming to introduce the basic knowledge of quantum information science. It can also be used as a textbook for quantum information courses for undergraduates majoring in quantum information or other related fields. As an introductory or general physics textbook, this book strives to be concise in its arrangement; for readers who wish to further explore quantum information in depth, the book also includes thought-provoking questions and reference materials focused on cutting-edge research content to provide guidance.