Optical computer storage media

The DVD (common abbreviation for digital video disc or digital versatile disc) is a digital optical disc data storage format. It was invented and developed in 1995 and first released on November 1, 1996, in Japan. The medium can store any kind of digital data and has been widely used to store video programs (watched using DVD players), software and other computer files. DVDs offer significantly higher storage capacity than compact discs (CD) while having the same dimensions. A standard single-layer DVD can store up to 4.7 GB of data, a dual-layer DVD up to 8.5 GB. Variants can store up to a maximum of 17.08 GB.

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.

Blu-ray (Blu-ray Disc or BD) is a digital optical disc data storage format designed to supersede the DVD format. It was invented and developed in 2005 and released worldwide on June 20, 2006, capable of storing several hours of high-definition video (HDTV 720p and 1080p). The main application of Blu-ray is as a medium for video material such as feature films and for the physical distribution of video games for the PlayStation 3, PlayStation 4, PlayStation 5, Xbox One, and Xbox Series X. The name refers to the blue laser (actually a violet laser) used to read the disc, which allows information to be stored at a greater density than is possible with the longer-wavelength red laser used for DVDs, resulting in an increased capacity.

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

The DualDisc is a type of double-sided optical disc product developed by a group of record companies including MJJ Productions Inc., EMI Music, Universal Music Group, Sony BMG Music Entertainment, Warner Music Group, and 5.1 Entertainment Group and later under the aegis of the Recording Industry Association of America (RIAA). It featured an audio layer intended to be compatible with CD players (but too thin to meet Red Book CD specifications) on one side and a standard DVD layer on the other. In this respect it was similar to, but distinct from, the DVDplus developed in Europe by Dieter Dierks and covered by European patents.

HD DVD (short for High Density Digital Versatile Disc) is an obsolete high-density optical disc format for storing data and playback of high-definition video. Supported principally by Toshiba, HD DVD was envisioned to be the successor to the standard DVD format, but lost out to Blu-ray, which was supported by Sony and others.

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.

Enhanced CD is a certification mark of the Recording Industry Association of America for various technologies that combine audio and computer data for use in both compact disc and CD-ROM players.