HD DVD or High-Definition DVD is a high-density optical disc format designed for the storage of data and high-definition video. HD DVD was designed by a consortium of companies (principally Toshiba and NEC) to be the successor to the standard DVD format.

HD DVD is derived from the same underlying technologies as DVD. Since all variants except the 3x DVD employed a blue laser with a shorter wavelength, it can store about 3¼ times as much data per layer as its predecessor (maximum capacity: 15 GB per layer instead of 4.7 GB per layer).

Much like the VHS vs. Betamax format war during the late 1970s and early 1980s, HD DVD was in a "format war" with rival format Blu-ray Disc to determine which of the two formats would become the leading carrier for high-definition content to consumers. In 2008, major content manufacturers and key retailers began withdrawing their support of the format. On February 19 2008, Toshiba made an official announcement that the company would no longer develop, manufacture, and market HD DVD players and recorders, ending the high definition optical disc format war.