The Digital Versatile Disc was created to fulfil the need for storage of high-quality video data. Two camps existed in the DVD technology arena: Philips and Sony were developing a new technology for storage of high-quality video, while simultaneously, Toshiba, Hitachi, and others were involved in developing a parallel technology that was incompatible with Sony’s technology. The two camps agreed to collaborate and the result was the DVD, in 1995.
DVDs can store up to six times as much as a CD, at 4.7 GB (if you consider a Kilobyte as 1,000 bytes), while using a disk of the same size. This was possible by using a laser of a smaller wavelength— 630 nanometres—and reducing the width of the tracks and the distance between them. The original DVD drive had a data transfer rate of 1.5 Megabytes per second.
Based on the number of recording surfaces, DVD is available as single side—single layer (also referred to as DVD5), single side— dual layer (DVD9), double side—single layer (DVD 10), and double side—dual layer (DVD 18). Dual-layer DVDs effectively doubled the storage capacity to 8.5 gigabytes (per side).
Based on the recording capabilities, DVDs can be categorised into DVD-ROM (read-only, usually the format for pre-manufactured DVDs), DVD-RAM (Random Access Memory, allowing reading and writing), DVD-R, and DVD+R (one-time recordable), DVD+RW & DVD-RW (rewriteable). The “+” and “-” in the nomenclature refer to the two incompatible formats offering the same features. Drives that are labelled as “super multi” are capable of playing all formats.