“IR” is an acronym for Infrared Radiation used to describe the wireless technology in devices or systems that convey data through infrared (IR) radiation. Infrared is electromagnetic energy at a wavelength or wavelengths somewhat longer than visible light, and is therefore generally invisible to the human eye.

Night-vision devices using active near-infrared illumination allow people or animals to be observed without the observer being detected. Infrared thermal-imaging cameras are used to acquire targets, for surveillance, night vision and tracking.