Infrared waves are electromagnetic waves whose wavelengths range between about 7 x 10^–7 and 10^–4 (0.0000007 and 0.0001) meters. Humans cannot see this kind of radiation, but they can sense it as heat. Because of our warm body temperature, we humans produce radiation mostly in the form of infrared waves. That is how some kinds of “night-vision goggles” work: They detect infrared waves coming from objects and people, even when there is not enough visible light for humans to see well.