This textbook is an English translation of the publication by the Japanese Society of Anti-Aging Medicine. It provides the basics and biology of aging science, followed by presenting clinical studies such as exercise, nutrition, mental health (brain, sleep), and treatment interventions. The book also discusses aging control and considers behavioral, environmental, and societal implications for healthy aging. The field of aging science is interdisciplinary, and there are much more uncertainties; thus, it is crucial to summarize what is currently known to set a foundation for future research.