This book offers a wide perspective on the fundamental and state-of-the-art knowledge in radiobiology, radiation oncology, and the connection between both fields. Chapters incorporate basic concepts of cancer biology and radiobiology with advances in radiotherapy in cancer treatment for various types of cancer. Chapters review one or more areas of radiation oncology with topics ranging from the application of radiotherapy in various cancers, the use of advanced techniques such as FLASH radiotherapy, applications of artificial intelligence in treatment planning, and more importantly, the current and potential strategies to reduce the toxic effects of radiation. This book incorporates interdisciplinary concepts by exploring recent approaches like radiogenomics for personalizing radiotherapy and the effects of the microbiome on radiation research. Teaching the basics of radiobiology and connections between the theory and the practical aspects of radiotherapy techniques, this book is a useful reference for cancer researchers, practitioners, interdisciplinary researchers in related fields, and students in radiation oncology and radiobiology. Through this integration of strong scientific foundations and clinical applicability, this book provides future research directions and rationales for readers looking to expand their knowledge about radiation with the most recent and essential data on the subject.