“Electromagnetic radiation is categorized by wavelength or frequency.” We know that infrared radiation is a form of electromagnetic radiation, which is longer in wavelength than visible light. Other types of electromagnetic radiation include x-rays, ultraviolet rays, radio waves, etc. Electromagnetic radiation is categorized by wavelength or frequency. Broadcast radio stations are identified by their frequency, usually in kilohertz (kHz) or megahertz (MHz). Other spectrums are categorized by their wavelength. The unit of measurement used is the micrometer, or micron, (m) which is one millionth of a meter. The visible part of the electromagnetic spectrum falls between 0.4 and 0.75 micrometers. We can see colors because we can discriminate between different wavelengths. The infrared cameras detect radiation in the 8 to 12 micrometer band we usually call “longwave” or between 3 to 5 micrometers and is termed “shortwave.” Most commercial infrared detectors today use the longwave spectrum.