Cathode ray tubes, which emit light, are used for televisions, computer monitors and the like. LED displays are used for cheap low resolution visual information. LCDs use the reflection of light for a similar goal. With the emergence of the internet these high-bandwidth solutions hold the key to global information sharing since the current infrastructure is not be capable of sustaining the emerging traffic. All hot bodies.
Infrared radiation is mainly heat .
All moderately hot bodies emit infrared. Infrared radiation is also used in optical fibres, like visible light. This was the original wavelength of the lasers used in this communications method. Infrared is also used for point to point communications. Infrared is also used for therapeutic purposes.