Optical disc composed of a phase change material, most often AgInSbTe, an alloy of silver, indium, antimony, and tellurium. Optical discs are most commonly used for storing music (e.g. for use in a CD player), video (e.g. for use in a Blu-ray player), or data and programs for personal computers (PC). The Optical Storage Technology Association (OSTA) promotes standardized optical storage formats. Although optical discs are more durable than earlier audio-visual and data storage formats, they are susceptible to environmental and daily-use damage. Libraries and archives enact optical media preservation procedures to ensure continued usability in the computer's optical disc drive or
DVD several formats developed for recording video on optical discs before the DVD. Optical recording technology was invented by David Paul Gregg and James Russell in 1958 and first patented in 1961. A consumer optical disc data format known as LaserDisc was developed in the United States, and first came to market in Atlanta, Georgia in 1978. It used much larger discs than the later formats. Due to the high cost of players and discs, consumer adoption of LaserDisc was very low in both North America and Europe, and was not widely used anywhere outside Japan and the more affluent areas