Infrared

Abbreviated IR.  The region of the electromagnetic spectrum between the long-wavelength extreme of the visible spectrum (~700nm) and the shortest microwaves (~1mm).

[box]Note: the International Commission on Illumination (CIE) recommended the following division:
IR-A: 700nm – 1400nm
IR-B: 1400nm – 3000nm
IR-C: 3000nm – 1mm[/box]