Infrared (IR) is electromagnetic light just beyond the visible spectrum. Consumer devices often use it for remote controls and other short-range command links because IR transmitters and receivers are cheap, simple, and reliable. Unlike radio systems, many IR controls require line of sight, so the signal is usually confined to a room or a direct path.
In cyber security, IR matters because older control channels can be overlooked. A device that accepts IR commands may let an attacker trigger actions without touching the network at all, especially if they can get close enough or aim a blaster at the target. Defenders should treat IR-controlled equipment as part of the attack surface: document it, restrict access where possible, and test whether unwanted commands can be sent from outside normal operating distance. In small hardware projects, IR is also a common way to build low-cost automation and proof-of-concept controllers.