A gamma ray is a type of high-energy radiation that comes from the decay of atomic nuclei. Unlike visible light, gamma rays have very short wavelengths and can penetrate most materials, making them powerful and difficult to shield against. They are often produced in nuclear reactions, such as those occurring in stars like our Sun or during events like supernovae. Gamma rays are used in various fields, including medicine and astronomy. In medicine, they are employed in treatments like radiation therapy to target and destroy cancer cells. In astronomy, scientists study gamma rays to learn more about extreme cosmic events, such as black holes and neutron stars.