What is a Compact Disc?
Since 1982, consumers have had access to one of the great breakthroughs in media storage technology: a slim, round, and shiny object known as the compact disc (CD). Also known as an optical disk, the 4.724 inch (120 mm) round polycarbonate CD has largely replaced less reliable but similar formats like the cassette tape and vinyl record as a unit for digitally stored audio. Despite its size, one standard compact disc may hold up to 80 minutes of music. It remains the most preferred and popular medium for audio recordings. The CD-ROM, a later version of the same technology, holds up to 700 megabytes (MB) of data and is widely used by individuals and businesses for archiving important documents, photographs, and software. A compact disc is a made of a combination of polycarbonate plastic and a reflective layer of aluminum, gold, or other metal. It was modeled after the Laserdisc (LD), a now-obsolete medium that resembles a vinyl record in its size and a CD in its composition. Information
