Infrared – the part of the invisible spectrum that is comprised of electromagnetic radiation with wavelengths of 800 nm to 1.
Infrared can be used in many different application depending who you are. For example if you need to be able to see at night you might use infrared goggles which would see things using the infrared light emitted by anything that is warm. Other uses of infrared light are motion tracking, cooking, communications, spectroscopy, meteorology, astronomy.
Infrared light can also be used in gaming through the use of an infrared LED. In an X-Box 360 remote control there is a high emitting infrared LED which sends commands by sending slightly different wavelengths of infrared light. Also in a Wii remote the sensor bar has 2 sets of infrared LED strips which the remote can see and using that it can plot its location in relation to the TV.