CDs (Compact Discs)

A compact disc, or CD, is a small, thin plastic disc imprinted with digital audio or, in the case of the compact disc read-only memory (CD-ROM), other digital information. A standard CD holds approximately 80 minutes of music or, in digital terms, 700 megabytes of data. Much like a turntable-style phonograph, the CD player spins the CD, and a laser “reads” the information. Early CDs allowed only playback, but today, recordable (CD-R) and rewriteable (CD-RW) versions are also available. Replacing vinyl records and cassette tapes, CDs dominated the music industry for more than a decade and helped usher in a new era of digital home entertainment.

From the 1950s to the 1970s, the engineers David Paul Gregg and James Russell invented laser disc technology, a method ...