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
Picture disc the discs as a medium for propaganda. Adolf Hitler and British fascist Oswald Mosley were each featured on their own special picture discs. Most of these records were made of a simple sheet of fairly thin printed cardboard with a very thin plastic coating and their audio quality was substandard. Some were more sturdy and well-made and they equaled or actually surpassed the audio quality of ordinary records, which were still made of a gritty shellac compound that introduced a lot of background noise. In 1933, RCA Victor in the U.S. issued a few typical cardboard-based picture records but was