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. In February 2008, after a protracted format war with rival Blu-ray Disc, Toshiba abandoned the format, announcing it no longer developed or manufactured HD DVD players or drives. The HD DVD physical disc specifications (but not the codecs) were still in use as the basis for the China Blue High-definition Disc (CBHD) 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 stored 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).
Read more about HD DVD: History, Recording Speed, Digital Rights Management, Interactive Content, HD DVD / Blu-ray Disc Comparison, Development