If you think infrared light is all about heat, try pointing your TV remote at yourself and pressing buttons.
Thermograms of buildings and houses are often used to help study heat loss or energy inefficienices; Image by Passivhaus Institut
For many people who are familiar with “infrared” light or radiation (which essentially mean the same thing), their association is often with heat. And for good reason. After all, we hear a lot of about infrared products as sources of heat these days in cooktops, space heaters, and saunas. You may also have heard how infrared light is used in thermal imaging (another way of saying "pictures of heat") in everything from military and law applications to making homes more energy efficient.
All of these ties with heat are valid, but that is only part of what infrared light can do. That’s because the range of infrared light spans an enormous swath of the electromagnetic spectrum – a thousand times bigger than the “visible light” we can see with our eyes. It’s so vast that scientists, engineers, and others who use it often break it up into smaller chunks. The type of infrared light that provides heat is known as “far infrared”. Another type is so-called near infrared, which has a bunch of applications in our day-to-day life as well and does not provide any heat. For example, near-infrared light is often used in fiber optics communications, which often brings you your phone, internet, and cable these days. But perhaps one of the most common uses for near infrared is in your TV, thus allowing you to remain firmly on the couch for as long as you want - though it won't keep you any warmer.