Optical Discs

DVD Digital Video Disk

The V also can be used to stand for "versatile" DVDs work in much the same way as CDs but they can store more information due to an improved storage algorithms. They can store up to 17 gigabytes. Which is a whole film.

The main advantage of these two storage types are that they are cheep and reasonably permanent. Most computers now come with a CD drive that handles both the CD and DVD format and the software on the machine usually handles both the reading and the writing process for both types of disk.

What writable DVD formats are available?

There are five kinds of writable DVD technology (DVD-R, DVD+R, DVD-RW, DVD+RW and DVD-RAM). Similar to CD-Recordable (CD-R), DVD-R and DVD+R discs are write-once incorporating a dye recording layer to which information is irreversibly written by means of a laser heating and altering it to create a pattern of marks mimicking the pits of a prerecorded (pressed/molded) DVD. DVD-RW and DVD+RW, on the other hand, closely resemble CD-ReWritable (CD-RW) by employing a phase-change recording layer that can be repeatedly changed and restored by the writing laser (approximately 1000 times). DVD-RAM also uses phase-change technology but can be rewritten roughly 100,000 times. With its hard sectors, random access capabilities and optional cartridge, DVD-RAM more closely resembles traditional disc-based storage media than do DVD-RW and DVD+RW. This separates DVD-RAM somewhat from the prerecorded DVD format that provides the basis for most DVD discs.

For more about optical disks see the OSTI website

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