Compact disc
Videos
The compact disc (CD) is a digital optical disc data storage format that was co-developed by Philips and Sony to store and play digital audio recordings. It uses the Compact Disc Digital Audio format which typically provides 74 minutes of audio on a disc. In later years, the compact disc was adapted for non-audio computer data storage purposes as CD-ROM and its derivatives. First released in Japan in October 1982, the CD was the second optical disc technology to be invented, after the much larger LaserDisc (LD). By 2007, 200 billion CDs had been sold worldwide.
The readable surface of a compact disc includes a spiral track wound tightly enough to cause light to diffract into a full visible spectrum.
Dutch inventor and Philips chief engineer Kees Schouhamer Immink was part of the team that produced the standard compact disc in 1980
Sony Discman D-E307CK portable CD player with 1-bit DAC
Pits and Lands of a compact disc under a microscope
CD-ROM
Videos
A CD-ROM is a type of read-only memory consisting of a pre-pressed optical compact disc that contains data computers can read—but not write or erase—CD-ROMs. Some CDs, called enhanced CDs, hold both computer data and audio with the latter capable of being played on a CD player, while data is only usable on a computer.
A CD-ROM in the tray of a partially open CD-ROM drive.
A CD-ROM can easily store the entirety of a paper encyclopedia's words and images, plus audio & video clips.
A view of a CD-ROM drive's disassembled laser system
The laser system of a CD-ROM drive