Picture of
dog in mid-infrared
Infrared (IR) radiation is a type of electromagnetic radiation (a wave with electricity) . The wave is longer than light which humans can see and shorter than microwaves. The word infrared means below red. It comes from the Latin word infra (meaning below) and the English word red. (Infrared light has a frequency below the frequency of red light.) Red light has the longest wavelength that human eyes can see. Infrared waves cannot be seen by the eye.