Infrared Radiation was discovered by Sir William Herschel in 1800. He named it from infra, meaning below, and red, the color at the lower end of the visible light spectrum. Infrared technology is used today in applications such as cameras, missiles and communications devices.

Infrared radiation is electromagnetic radiation generated by thermal agitation. As the temperature of an object is increased, the atoms and molecules within an object begin to move faster. More infrared radiation is generated as the molecules increase their motion. Infrared is sometimes referred to as heat radiation. This is a misnomer, as any electromagnetic radiation induces heat as it strikes an object. Infrared radiation is a true electromagnetic radiation. It travels in a straight line through a vacuum or any physical medium. It does not travel via conduction or thermal convection.

Infrared radiation, just as any electromagnetic radiation, is capable of being optically directed and focused.

The infrared spectrum consists of three regions, with their names determined by their distance from the visible light spectrum. The near region has a wavelength of .72 to 1.5. The intermediate region runs from 1.5 to 5.6 wavelengths. The far region runs from 5.6 to 1000 wavelengths.