The authors explain quantum communication theory from an engineering(application) viewpoint including the advanced quantum communication schemes and give an overview on the security of these systems. Each section of the book addresses an area of major researchof quantuminformation theory and quantum communication networks. The authors present the fundamental theoretical results of quantum information theory, and simultaneously present the details of advanced quantum communication protocols with clear mathematical and information theoretical background. The book will describe the engineering principles and questions of advanced communication network, quantum-Internet networks and intelligent quantum-probabilistic network controlling elements. The future quantum communication systems will integrate free-space and fiber-based ccommunication systems; However, the communication between them is the challenge. This book will bridge the gap between quantum physics, quantum information theory and practical engineering.