Short for Sony and Phillips Digital Interconnect Format, the S/PDIF or SPDIF interface transmits digital audio in a compressed form between audio equipment and home theater systems. The S/PDIF interface can utilize a coaxial cable or a fiber optic cable to transmit the audio. Common equipment to use this interface are DVD (digital versatile disc) players and CD (compact disc) players, connecting to a home theater system for Dolby Digital or DTS (Digital Theater Sound) surround sound. High-quality sound cards and laptops also have this connector. The first picture shows what the SPDIF connector may look like on your computer motherboard.
The audio transmitted through the S/PDIF interface is defined by the IEC (International Electrotechnical Commission) 61937 standard. The common formats transmitted are the 48 kHz sample rate, which is used in DAT (Digital Audio Tape), and the 44.1 kHz sample rate (used in CD audio). The second picture shows a fiber optic connection on the back of audio equipment.