DVD-R, spoken as "DVD minus R," is one of the six recordable versions of a DVD-ROM. The full form of DVD is Digital Versatile/Video Disc, and ROM stands for Read-only Memory. DVD-R media stands for DVD recordable. The first DVD R format, which was introduced in the market in 1997, came with a 3.5 GB disc capacity. Now, thanks to the rapid progress in electronics and technology, the format has been improved to a capacity of 4.7 gigabytes (GB).

With a variety of formats available for optical data storage, for instance, DVD-R for General, DVD-R for Authoring, DVD-RAM, DVD-RW, DVD+RW, and DVD+R, users are usually faced with the dilemma of choosing the right DVD format that is compatible with their existing systems. The variations in formats explain the ways in which manufacturers store data on the disc.

DVD-R and DVD+R Formats

DVD-R, developed by Pioneer in 1997, is a recordable DVD format similar to CD-R. With this format, DVDs can store up to 4.7 billion bytes of data on a single side. This format is designed to be compatible with most DVD players and drives. DVD-R format is a write-once format that allows users to write, after which the disc is permanently frozen with that information.

DVD+R, created by the "DVD+RW Alliance," is another optical data storage format that has been designed to be similar to, but incompatible with, the DVD-R standard. A DVD+R is also in a write-once format with 4.7 GB of storage. This disc is generally used for non-volatile data storage or for video applications.

DVD-RW and DVD+RW are re-recordable formats, which helps users to erase and rewrite information 1000 times on the disc. DVD+R and DVD+RW formats are supported by Philips, Sony, Dell, Microsoft, Hewlett-Packard, Dell, Ricoh, Yamaha, and others. DVD-R and DVD-RW are supported by Panasonic, Toshiba, Apple Computer, Hitachi, NEC, Pioneer, Samsung, and Sharp.

The difference between DVD-R and DVD-RW, and between DVD+R and DVD+RW is that they are nothing but sister discs. The main difference is that one is writeable once, while the other is writeable multiple times.

Now, the main difference is the "minus" and "plus" signs. The DVD-R/RW is primarily used by Apple and Pioneer. The "minus" discs can only be written on one layer of the disc surface. This format, even though supported by the DVD forum, is not an industry standard. Another difference is that DVD-R/RW discs are cheaper than the DVD+R/RW formats.

The DVD+R/RW format discs can be written in multiple layers. This feature gives a slightly better and more disc storage than the "minus" format. This additional ability makes them slightly more expensive than the "minus" discs.

DVD-R and DVD+R are two competing technologies based on the CD-RW technology and use different formats. DVD-R/RW is supported by the DVD Forum, whereas DVD+R/RW is not supported by the DVD Forum. But this forum, which is an assembly of hardware and software developers and computer peripheral manufacturers, does not posses any power to set industry standards. Hence, the issue of superiority between the two formats becomes a market-driven issue.

Blu-Ray Media

DVD-R media has now been outmoded, thanks to the advent of Blu-ray Disc. This new optical disc storage medium has a plastic optical disc, which is 12 cm in diameter. These discs have a capacity to hold 25 GB per layer. This new DVD format will also be available with dual-layer discs, packing 50 GB capacity. It is expected that discs with additional layers will be introduced in the future.

In Blu-Ray, blue laser is used to read the disc. This technologically advanced ray helps in storing information at a greater density, which is generally not feasible with the longer wavelength red laser used for DVDs.