From Wikipedia.....
Blu-ray Disc (also known as Blu-ray or BD) is an optical disc storage media format. Its main uses are high-definition video and data storage. The disc has the same dimensions as a standard DVD.
The name Blu-ray Disc is derived from the blue-violet laser used to read and write this type of disc. Because of its shorter wavelength (405 nm), substantially more data can be stored on a Blu-ray Disc than on the DVD format, which uses a red (650 nm) laser. A Blu-ray Disc can store 50 GB, almost six times the capacity of a DVD.
Blu-ray was developed by the Blu-ray Disc Association, a group of companies representing consumer electronics, computer hardware, and motion picture production. The standard is covered by several patents belonging to different companies. As of March 2007, a joint licensing agreement for all the relevant patents had not yet been finalized.
As of February 19, 2008, more than 450 Blu-ray Disc titles have been released in the United States, and more than 250 in Japan.
Long locked in a format war with HD DVD, Blu-ray Disc emerged the winner on February 19, 2008 when Toshiba - the main driving force behind HD-DVD - announced it would no longer develop, manufacture and market HD DVD players and recorders.
Some analysts believe that Sony's Playstation 3 console played an important role in the format war, as it was based largely on Blu-Ray technology.
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http://en.wikipedia.org/wiki/Blu_ray