Blu-ray Disc (also known as Blu-ray or BD)

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 or CD.

The name Blu-ray Disc is derived from the blue laser (violet coloured) 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 dual layer Blu-ray Disc can store 50 GB, almost six times the capacity of a dual layer DVD.

Blu-ray Disc was developed by the Blu-ray Disc Association, a group of companies representing consumer electronics, computer hardware, and motion picture production. As of June 20, 2008 more than 630[2] Blu-ray Disc titles have been released in the United States and more than 390[3] Blu-ray Disc titles have been released in Japan.

During the high definition optical disc format war, Blu-ray Disc competed with the HD DVD format. On February 19, 2008, Toshiba — the main company supporting HD DVD — announced it would no longer develop, manufacture and market HD DVD players and recorders,[4] leading almost all other HD DVD supporters to follow suit, effectively naming Blu-ray the winner of the format war.

Definition source: http://en.wikipedia.org/wiki/Blu-ray_Disc