infrared
Invisible electromagnetic radiation with a wavelength between approximately 0.75 micrometres and 1 millimetre. Infrared occurs between the red end of the visible light spectrum and microwaves. All things over a certain temperature (absolute zero) absorb and emit infrared radiation. Infrared radiation and observing technologies are used in many industries from medicine to finding people buried under rubble and by the military and others in night-vision goggles.
