Passive Infrared (PIR) technology detects infrared radiation emitted by objects, particularly warm bodies like humans and animals. It works by sensing changes in heat within its field of view, allowing it to identify movement. PIR sensors are commonly used in security systems, automatic lighting, and energy-saving applications. Unlike active infrared systems, which emit their own infrared signals, PIR sensors are "passive" because they only receive and respond to infrared radiation. This makes them energy-efficient and reliable for various applications, including home security, motion-activated lights, and smart home devices.