TOSLINK connector in applications of Toslink:TOSLINK (from "Toshiba Link") is a standardized optical fiber connection system.Also known generically as an "optical audio cable", its most common use is in consumer audio equipment (via a "digital optical" socket), where it carries a digital audio stream from components such as MiniDisc, CD and DVD players, DAT recorders, computers, and modern video game consoles, to an AV receiver that can decode the stream of audio and output it through a set of loudspeakers. Although TOSLINK supports several different media formats and physical standards, digital audio connections using the rectangular EIAJ/JEITA RC-5720 (also CP-1201 and JIS C5974-1993 F05) connector are by far the most common.The optical signal is a red light, with a peak wavelength λ of 650 nm.Depending on the type of modulated signal being carried, other optical wavelengths may be present.

Toshiba originally created TOSLINK to connect their CD players to the receivers they manufactured, for PCM audio streams. It was soon adopted by manufacturers of most CD players. Early TOSLINK systems used the raw PCM data from the CD player; the S/PDIF standard has now become nearly universal for audio streams. It can often be found on DVD players and some game consoles to connect the digital audio stream to Dolby Digital/DTS decoders.

The name is a registered trademark of Toshiba, created from TOShiba-LINK. Variations of the name, such as TOSlink, TosLink, and Tos-link, are also seen, while the official generic name for the standard is EIAJ optical.

Other terms are sometimes used for technology similar to TOSLINK, such as ADAT Lightpipe or simply ADAT Optical. These are most often seen in the professional music/audio industry. While the ADAT Lightpipe format uses the same JIS F05 connectors as TOSLINK, the ADAT Lightpipe data format is not compatible with S/PDIF.