DVD (Digital Video Disc, now Digital Versatile Disc) is a format of optical storage. A disc can store up to 4.7GB of data on one side, and it works by reflecting a laser to save and view data.
The writable layer of a DVD disc has a spiral track of data. The track circles from the inside of the disc to outside, and contain pits. There is 740 nanometers (10^-9 m) between one data track and the next.
The track pits are:
- 320 nanometers wide
- Minimum of 400 nanometers long
- 120 nanometers deep
2 competing developments
Multimedia CD (MMCD) and Super Disc (SD)
2 Developments were combined
Slight variations of DVD exist due to the widespread support from a range of electronic companies.
- DVD+ (pronounced "DVD-plus")
- DVD- (pronounced "DVD-minus")
Differences Between Variations
The differences between DVD+ and DVD- are small, it is a rare case that a DVD- player may not be compatible with a DVD+ disc. DVD- discs are less costly than DVD+ discs to obtain, however require more time to burn data on to.