Question: what is radiation

Frank Longford answered on 15 Mar 2015:

Radiation is the general term given to particles and electromagnetic waves of different frequencies that transmit energy throughout space (that’s 3D space, not space above us in the sky). There are many different types of radiation, you may have heard of infrared radiation (IR), microwave radiation, x-rays, gamma rays and alpha and beta particles. Most radiation comes from the sun and radioactive decay of unstable elements such as uranium and radium. Radiation with a lot of energy can be harmful because of the way it interacts with molecules in our cells. Mutations can occur when radiation ionises DNA, which can lead to cancer.
However, low energy radiation like radio waves have been used safely by humans for a long time – in fact visual light is a form of radiation and we use that to see with!