What is infrared radiation?

Infrared radiation (IR radiation) - also referred to as thermal radiation - is part of the electromagnetic spectrum. It follows the visible radiation in the direction of longer wavelengths ranging from 780 nanometres to 1 millimetre. IR radiation is divided into the short wavelength IR-A radiation with a wavelength range from 780 to 1400 nanometres, the IR-B radiation (1400 to 3000 nanometres) and the long wavelength IR-C radiation (3000 nanometres to 1 millimetre). The most important natural source of IR radiation is the sun.