Radioactivity is a property of the atomic nuclei to decay and thereby release radiation. Many atoms split when they are bombarded with neutrons, and others decay spontaneously. In both the cases, the radiation of radioactive material takes place. This radiation occurs in three forms. The alpha rays can reach only up to a few centimetres. The beta rays are made of electrons resulting from the splitting of atomic nuclei. They can go up to 1m and are stopped by metallic foils. The gamma rays are bundled energy released in the decay and are very dangerous. Even thick lead plates can only partly stop them. They can penetrate the cells of our body and can modify or destroy them.