Infrared
Light = waves of electromagnetic energy that travel through space.
infrared light, invisible to the eye, can be detected as the sensation of warmth on the skin. Near infrared light is used in photography to produce unusual effects such as the whitening of foliage or human skin. It extends from the long wavelength, or red, end of the visible-light range to the microwave range. The far spectrum of infrared is used for thermal imaging.