Almost everyone and everything in the world is radioactive, from bananas in the kitchen to the bricks and concrete in homes, as well as most things that can be eaten, worn, played with, or touched every day. Radiation can be found everywhere since the universe began and Earth first formed. But what does 'radioactive' really mean? ""Radioactivity"" explains the science behind radiation, from the radiation in the body to the radiation in the environment; how radiation can create energy and cause destruction; and, how it saves lives every day.