Compact disc

A CD single is a music single in the form of a compact disc (CD). Originally the CD single standard (as defined in the Red Book) was an 8 cm (3-inch) "mini CD" (CD3); later on the term referred to any single recorded onto a CD of any size, particularly the 12 cm (5-inch) "full-size" disc (CD5). From a technical viewpoint, a CD single is identical to any other audio CD. The format started gaining popularity in the early 1990s, but quickly declined in the early and mid 2000s, in favor of digital downloaded singles and CD albums.

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 (including audio CDs, CD-ROMs and CD-Rs) had been sold worldwide.

Princo Corp. v. ITC, 616 F.3d 1318 (Fed. Cir. 2010) was a 2010 decision of the United States Court of Appeals for the Federal Circuit, that sought to narrow the defense of patent misuse to claims for patent infringement. Princo held that a party asserting the defense of patent misuse, absent a case of so-called per se misuse, must prove both "leveraging" of the patent being enforced against it and a substantial anticompetitive effect outside the legitimate scope of that patent right. In so ruling, the court emphasized that the misuse alleged must involve the patent in suit, not another patent.

Mini CDs, or pocket CDs, are CDs with a smaller diameter and one-third the storage capacity of a standard 120 mm disc.

An optical disc is a flat, usually disc-shaped object that stores information in the form of physical variations on its surface that can be read with the aid of a beam of light. Optical discs can be reflective, where the light source and detector are on the same side of the disc, or transmissive, where light shines through the disc to be detected on the other side.

Super Audio CD (SACD) is an optical disc format for audio storage introduced in 1999. It was developed jointly by Sony and Philips Electronics and intended to be the successor to the compact disc (CD) format.

CD-R (Compact disc-recordable) is a digital optical disc storage format. A CD-R disc is a compact disc that can only be written once and read arbitrarily many times.

The Compact Disc-Interactive (CD-I, later CD-i) is a digital optical disc data storage format as well as a hardware platform, co-developed and marketed by Dutch company Philips and Japanese company Sony. It was created as an extension of CDDA and CD-ROM and specified in the Green Book specifications, co-developed by Philips and Sony, to combine audio, text and graphics. The two companies initially expected to impact the education/training, point of sale, and home entertainment industries, but the CD-i is largely remembered today for its video games.

On an optical disc, a track (CD) or title (DVD) is a subdivision of its content. Specifically, it is a consecutive set of sectors (called "timecode frames" on audio tracks) on the disc containing a block of data. One session may contain one or more tracks of the same or different types. There are several kinds of tracks, and there is also a sub-track index for finding points within a track.

High Definition Compatible Digital (HDCD) is a proprietary audio encode-decode process that claims to provide increased dynamic range over that of standard Compact Disc Digital Audio, while retaining backward compatibility with existing compact disc players.