Its natural and all around us. It comes up from the ground, down through the atmosphere, and even from within our own bodies. It can be man-made too. But its nothing new. Its been present since the birth of the planet. Its radiation, and radiation is, quite simply, part of our lives. Naturally-occurring radioactive materials were discovered in 1896. Less than 40 years later, physicists discovered that radioactive elements can be artificially created. Within a decade of this discovery, scientists had split the atom. These findings allow us to use radioactive materials for beneficial purposes, such as generating electricity and diagnosing and treating medical problems. For these many benefits, excessive radiation exposure can also threaten our health and the quality of our environment. We cannot eliminate radiation from our environment. We can, however, reduce our risks by controlling, to some extent, our exposure to it. This booklet presents the major sources and uses of radiation, the risks from exposure, and how we can limit and reduce these risks.