Gamma radiation is a type of electromagnetic radiation emitted by the nucleus of an atom during radioactive decay. It has the highest energy and shortest wavelength of all types of electromagnetic radiation. Gamma rays are typically produced by nuclear decay, nuclear fusion, and certain types of high-energy particle collisions. Gamma radiation is highly penetrating and can travel long distances in air, water, or other materials. Gamma radiation can be harmful to humans if it is not properly shielded or monitored.