IR, also infrared, is light just outside of the visible range. The name “infrared” comes from the Latin prefix “infra”, meaning “below” and the word “red”. The word directly means "below red", which is exactly what infrared is in terms of its frequency.
The infrared light ranges from near- to far-infrared, first being closer to the visible light and the latter - microwaves. Near-infrared is what we know as heat, so although we cannot see it, we can most certainly feel it.
Far-infrared, on the other hand, cannot be registered with any of the human senses. The frequency is used in remote control technology to transmit information. The most popular devices using this technology are TV remote controls.
The technology is also used in night-vision devices. It allows users to see in the dark, without being seen themselves - at least not without special equipment. At Wiseled, infrared is used in our Xtruder RAVEN - an aid to driver’s vision enhancement.