HD DVD is an obsolete high-density optical disc format for storing data and playback of high-definition video. Supported principally by Toshiba, HD DVD was envisioned to be the successor to the standard DVD format, but lost to Blu-ray, supported by Sony and others.
In November 2006, Microsoft released an HD DVD player for their Xbox 360 game console for $199. It came packaged with King Kong and could only play movies.
Although HD DVD and Blu-ray used near-identical translucent keep cases for most pre-recorded releases, they were normally coloured red for the former and blue for the latter.
Internal optical disc drive from LG playing both, HD DVD and Blu-ray disks
An optical disc is a flat, usually disc-shaped object that stores information in the form of physical variations on its surface that can be read with the aid of a beam of light. Optical discs can be reflective, where the light source and detector are on the same side of the disc, or transmissive, where light shines through the disc to be detected on the other side.
The optical lens of a compact disc drive.
LaserCard made by Drexler Technology Corporation.
Optical discs are not vulnerable to water.
An earlier analog optical disc recorded in 1935 for Lichttonorgel [de] (sampling organ)
![An earlier analog optical disc recorded in 1935 for Lichttonorgel [de] (sampling organ)](https://upload.wikimedia.org/wikipedia/commons/thumb/5/55/Lichttonorgelversuchsscheibe.jpg/640px-Lichttonorgelversuchsscheibe.jpg)