What is Radiation?

Radiation is an energy in the form of electro-magnetic waves or particulate matter, traveling in the air. Radiation is energy that comes from a source and travels through some material or through space. Light, heat and sound are types of radiation. If a nucleus is unstable for any reason, it will emit and absorb particles. There are many types of radiation and they are all pertinent to everyday life and health as well as nuclear physical applications.