Radiation is all around us and naturally present in our environment and has been since before the birth of the planet. Radiation occurs in nature, but it can also be produced artificially, as in medical X-rays, microwaves for cooking and for nuclear energy. Radiation can be either beneficial or harmful, depending on its use and control. Therefore, regulation of certain radioactive sources is necessary so that people are protected from unnecessary or excessive exposures. This book examines the major sources and uses of radiation, the risks from exposure and how we can reduce these risks.