Infrared light, as radiated by the Sun, lies between the Visible and Microwave sectors of the electromagnetic spectrum. The electromagnetic spectrum includes Gamma Rays, X-rays, Ultraviolet, Visible, Infrared, Microwaves and Radio Waves. The earths atmosphere allows Infrared rays in the 6 to 14 micron level to safely reach its surface.

The Infrared electromagnetic spectrum is divided into three distinct segments based on wavelength and is measured in microns. Near Infrared, 0.75 to 1.5 microns, is that area of the spectrum that is closest in wavelength to Visible light. Medium Infrared, 1.5 to 4 microns, is that area of the spectrum between Near Infrared and FAR Infrared. FAR Infrared (FIR), 4 to 1000 microns is that area that is closest to the Microwave area of the electromagnetic spectrum.

Infrared is all around us. Even the human body radiates infrared through the skin at 2 to 50 microns, with most of this output being at the 9.4-micron level. The 9.4 average micron level output of the human body works hand in hand with FAR Infrared heat or energy.