Radioactivity is the process by which unstable atomic nuclei lose energy by emitting radiation. This phenomenon occurs naturally in certain elements, such as Uranium and Radium, and can also be induced artificially. The emitted radiation can take the form of alpha particles, beta particles, or gamma rays, each with distinct properties and effects. The study of radioactivity has significant implications in various fields, including medicine, where it is used in radiotherapy to treat cancer, and in energy production, particularly in nuclear reactors. Understanding radioactivity is crucial for safety and environmental protection, as it can pose health risks if not properly managed.