Optical digital out is the term used to describe an output connection on electronic devices--including computers, televisions and CD (compact disc) and DVD (digital versatile disc) players--that allows digital audio signals to be transmitted via pulses of light rather than copper wire.
Optical digital out first appeared in the United States in 1983, when Toshiba introduced CD players capable of transmitting digital audio signals by pulses of red light under the trade name TOSLINK.
Connectors for optical digital out--otherwise known as fiber optic--are typically square and molded onto the cable. As such, they cannot be resoldered at home and must be bought ready-made. Adapters that convert optical digital out to coaxial digital out--via an RC connector--fill another slot in these systems.
Optical digital out connections are immune to interference from electromagnetic and RF (radio frequency) sources, and the signal does not weaken over distances of up to 130 feet.