This book provides a comprehensive overview of the principles and applications of immunotherapy and radiotherapy in the treatment of cancer. It covers the basic concepts of immunotherapy, immunology, radiation physics, radiobiology, and tumor biology, as well as their clinical aspects, such as patient selection, treatment planning, delivery techniques, toxicity management, outcome evaluation, and neoadjuvant approaches. The book also discusses the current challenges and future directions in the field, such as combining immunotherapy and radiotherapy, optimizing the timing and sequencing of treatments, developing novel biomarkers and predictive models, and implementing personalized and adaptive approaches. The book is intended for oncologists, radiation oncologists, medical physicists, radiation therapists, immunologists, researchers, students, and anyone interested in learning more about this rapidly evolving area of cancer therapy.