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A digital versatile disc, which many people refer to by its acronym "DVD," is a plastic disc usually 4.7 inches (12 cm) in diameter that uses microscopic pits on the surface of the disc to store information. An aluminum coating covers the pits so that a thin laser can read the information. They can contain anywhere from 4.7 to 17.0 gigabytes of data. Due to their large storage capacity, digital versatile discs are popular for data storage and are also a common medium for the storage and distribution of video, especially movies.
Digital versatile discs are very similar to compact discs, or CDs, but can hold as much as 26 times more data. They rely on the same laser technology that CDs employ, but since the laser that a DVD player uses is much thinner than the laser in a CD player, the pits that store the data can be much smaller. DVDs can also have a translucent first layer, which allows the laser to access a second layer of data underneath, doubling the capacity. A digital versatile disc can also be double-sided, which doubles the storage capacity again.
There are several different kinds of digital versatile disc, although they all use the same basic technology. DVD-Rs allow a user to write information to the disc one time, while DVD-RAM, DVD-RW, and DVD+RWs allow the user to write information to the disc multiple times. DVD-ROM discs do not allow any writing — they can only be read. DVD video and DVD audio discs are also common, allowing for the distribution of video and audio content respectively.
The digital versatile disc format became popular during the mid-1990s. Initially, several different manufacturers were developing variants of the same technology without an industry-wide standard. Many of the major computer manufacturers, not wanting to get caught in a battle between different formats, refused to utilize the technology until manufacturers of the discs could agree upon a single standard. In 1995, these manufacturers did agree on a standard, and today's digital versatile disc format is the result.
Digital versatile disc technology became popular in the international market very shortly after its initial release in Japan in 1996. At first, its large storage capacity made it popular among software developers, but it's popularity as a means of distributing video followed closely thereafter. DVDs eventually surpassed VHS tapes as the leading format for video distribution to the home market. This was largely due to the improved picture and sound quality that the digital versatile disc offered home movie viewers. The large storage capacity allowed more image and sound information to be included.
New technologies have since appeared to compete with the digital versatile disc. One of these is the Blu-ray disc, which utilizes a laser that is even thinner than the one that DVD technology uses, thus allowing for greater data storage. This laser's shorter wavelength gives it a blue color, rather than the red color of a DVD laser.
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