The purpose of Understanding Radiation Science: Basic Nuclear and Health Physics is to provide the reader a basic understanding of radiation science. Therefore, basic nuclear physics and health physics principles are presented through chapters on atomic structure, types of radiation, terminology and units, radiation biology, exposure and controls, background radiation, personnel monitoring, and radiation instrumentation. The book concludes with chapters on historical events and definitions. This book provides introductory information for students starting there education in nuclear physics, health physics and nuclear engineering. The material covered in this book is appropriate for all types of radiation workers. Persons studying to take the health physics certification exam, radiation protection technologist exam, or the certifying examinations to become radiologic technologist, radiation therapy technologists, ultrasound technologists, or nuclear medicine technologists will find this information most useful.