Thermal imaging

[Couch Potatoe]

the use of special electronic equipment, in conditions in which it is difficult to see, to create a picture based on the heat produced by a person or object

[Mark Zuckerberg]

Thermal imaging is a method of improving visibility of objects in a dark environment by detecting the objects infrared radiation and creating an image based on that information. The infrared energy emitted by an object is known as its heat signature. In general, the hotter an object is, the more radiation it emits.