HD DVD (short for High-Definition/Density DVD) is a discontinued high-density optical disc format for storing data and high-definition video. Supported principally by Toshiba, HD DVD was envisioned to be the successor to the standard DVD format. However, in February 2008, after a protracted high definition optical disc format war with rival Blu-ray Disc, Toshiba abandoned the format, announcing it would no longer develop or manufacture HD DVD players or drives. However, the HD DVD physical disc specifications (but not the codecs) are still in use as the basis for the CBHD (China Blue High-Definition Disc) formerly called CH-DVD. The HD DVD Promotion Group was dissolved on March 28, 2008.

Because all variants except 3× DVD and HD REC employed a blue laser with a shorter wavelength, HD DVD could store about 3.2 times as much data per layer as its predecessor (maximum capacity: 15 GB per layer instead of 4.7 GB per layer).

In the mid 1990s, commercial HDTV sets started to enter a larger market. However, there was no inexpensive way to record or play back HD content. JVC's D-VHS and Sony's HDCAM formats could store that amount of data, but were neither popular nor well-known. However, it was well known that using lasers with shorter wavelengths would yield optical storage with higher density. Shuji Nakamura invented practical blue laser diodes, however, a lengthy patent lawsuit delayed commercial introduction.

DVD-RAM (DVD–Random Access Memory) is a disc specification presented in 1996 by the DVD Forum, which specifies rewritable DVD-RAM media and the appropriate DVD writers. DVD-RAM media have been used in computers as well as camcorders and personal video recorders since 1998.

DVD-RAM is one of three competing technologies for rewritable DVDs. Its competitors are DVD-RW and DVD+RW. DVD-RAM technology provides excellent data integrity, data retention and damage protection through a number of mechanisms and properties. Therefore, DVD-RAM is perceived by some people^[who?] to be better than the other DVD technologies for traditional computer usage tasks such as general data storage, and especially data backup and archival. The Mount Rainier Format standard and SecurDisc for DVD+/-RW (which also works on DVD-RAM, CD-R, and CD-RW) somewhat lessens the DVD-RAM format's perceived advantage in the data integrity category, but not in the data retention or damage protection categories.

DVD-RAM has a larger presence in camcorders and set-top boxes than in computers^{[citation needed]}, although the popularity of DVD-RAM in these devices can be explained by its being very easily written to and erased, which for example allows extensive in-camera editing.