Optical Cables

Optical cables are a leap forward in digital information transfer technology. Unlike regular cables which use electrical current, or digital cables, which use electronic data like a computer, optical cables use light sent through long optical fibres to transfer digital information. They are most commonly used to carry a digital audio streams from devices such as MiniDisc, CD and DVD players, DAT recorders, computers, and modern video game consoles, to an AV receiver, such as a television or amplifier that can decode the stream of audio and output it through a set of speakers. 

TOSlink
Toshiba were the first company to employ optical fibre technology to transfer digital audio between their devices, and the connectors they designed for this purpose became known as TOSlink connectors, although these are now the standard connector design, with many manufacturers cloning the design.