Infrared light has a range of wavelengths. ‘Near infrared’ has shorter wavelengths and is used for devices such as night vision goggles. ‘Far infrared’ has longer wavelengths and is used for things such as thermal imaging. Infrared can also be used for some short range ‘line of sight’ communication, such as TV remote controls.
Image acknowledgement: Diagram showing how infrared detectors help us ‘see’ heat. University of Waikato.