DVD ROM

DVD

The backside of a Sony DADC-manufactured DVD
Media type	Optical disc
Encoding	DVD-ROM and DVD-R(W) use one encoding, DVD-RAM and DVD+R(W) uses another
Capacity	4.7 GB (single-sided, single-layer – common) 8.5 GB (single-sided, double-layer) 9.4 GB (double-sided, single-layer) 17.08 GB (double-sided, double-layer – rare)
Read mechanism	650 nm laser, 10.5 Mbit/s (1×)
Write mechanism	650 nm laser with a focused beam more powerful than one used for reading, 10.5 Mbit/s (1×)
Standard	DVD Forum's DVD Books and DVD+RW Alliance specifications
Developed by	Panasonic, Philips, Sony, Toshiba
Weight	16 grams (246 grains)
Extended to	DVD+RW, DVD-RAM (Fixed-track writable media)

DVD (an abbreviation of "digital versatile disc" or "digital video disc") is a digital optical disc storage format invented and developed by Panasonic, Philips, Sony and Toshiba in 1995. The medium can store any kind of digital data and is 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.

Pre-recorded DVDs are mass-produced using molding machines that physically stamp data onto the DVD. Such discs are a form of DVD-ROM because data can only be read and not written or erased. Blank recordable DVD discs (DVD-R and DVD+R) can be recorded once using a DVD recorder and then function as a DVD-ROM. Rewritable DVDs (DVD-RW, DVD+RW, and DVD-RAM) can be recorded and erased many times.

DVDs are used in DVD-Video consumer digital video format and in DVD-Audio consumer digital audio format as well as for authoring DVD discs written in a special AVCHD format to hold high definition material (often in conjunction with AVCHD format camcorders). DVDs containing other types of information may be referred to as DVD data discs.

The Oxford English Dictionary comments that, "In 1995 rival manufacturers of the product initially named digital video disc agreed that, in order to emphasize the flexibility of the format for multimedia applications, the preferred abbreviation DVD would be understood to denote digital versatile disc." The OED also states that in 1995, "The companies said the official name of the format will simply be DVD. Toshiba had been using the name ‘digital video disk’, but that was switched to ‘digital versatile disk’ after computer companies complained that it left out their applications."