DVD

DVD (an abbreviation of "digital versatile disc" or "digital video disc") is a digital optical disc storage format invented and developed in 1995 and released in late 1996. The medium can store any kind of digital data and was widely used for software and other computer files as well as video programs watched using DVD players. DVDs offer higher storage capacity than compact discs while having the same dimensions.

Etymology

The term "DVD" originally stood for "Digital Video Disc". Some members of the DVD Forum (see 1.2 DVD Forum and formats) believe that it should stand for "Digital Versatile Disc" to reflect its widespread use for non-video applications. Toshiba, which created the disc, says the officially adopted name of the format is simply "DVD"; it is also known as "DVD Format".

History

DVDs are of the same diameter and thickness as CDs, and they are made using similar methods and materials. The disc reflects the light from the laser, with deviations in the reflective layer. The reading device then interprets these deviations.

Dual-layer recording

Dual-layer recording (sometimes also known as double-layer recording) allows DVD-R and DVD+R discs to store significantly more data—up to 8.54 gigabytes per disc, compared with 4.7 gigabytes for single-layer discs. Along with this, DVD-DLs have slower write speeds as compared to ordinary DVDs. When the layer is in use, the drive must focus the laser through the first semi-transparent layer to reach the second layer. Once the first layer has been recorded, the laser re-focuses to burn the second layer.

Related terms

• DVD-R: A DVD recordable format.
• DVD+R: A format of DVD which can be recorded once and read arbitrarily many times.
• DVD-RW: A rewritable format of DVD.
• DVD+RW: A rewritable format of DVD that is direct competition to DVD-RW.
• DVD-RAM: A DVD random access memory.

See also

• Blu-ray
• CD
• Optical disc

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