This book highlights a comprehensive coverage of the science and technology of multi-orbit inter-satellite links. It describes the fundamental concepts and system requirements, presents the architecture and measurement principles and demonstrates the anti-interference design, access and slot planning, network transmission and routing, calibration and test evaluation, as well as applications for measurement and communication. Recent advances in theoretical research on precision measurement and communication are presented. The book serves as a reference for professionals involved in designing space-based information systems or developing satellite-ground equipment or services based on inter-satellite links. Additionally, it is also a valuable resource for teachers and graduate students in related majors.