whatr is a blue ray dvd

please visit http://en.wikipedia.org/wiki/Blue_ray_disk for detailed info

A Blu-ray Disc is a high-density optical disc format for the storage of digital media, including high-definition video. The name Blu-ray Disc (BD) is derived from the blue-violet laser it uses to read and write for high data storage density. A Blu-ray Disc can store substantially more data than the common DVD format, because of the shorter wavelength (405 nm) of the blue-violet laser (DVDs use a 650-nm-wavelength red laser and CDs use an infrared 780 nm laser), which allows more information to be stored digitally in the same amount of space. In comparison to HD DVD, which also uses a blue laser, Blu-ray Disc has more information capacity per layer (currently 25 GB, but test media is up to 33 GB). However Blu-Ray discs are expected to be more expensive than HD-DVD discs, at least initially. Sony has released 50 GB recordable BDs and will soon be releasing 50GB BRD media discs.[1] In August 2006, TDK demonstrated a Blu-ray Disc with a 200 GB capacity.[2] The Blu-ray Disc is a similar format to PDD, another optical disc format developed by Sony (which has been available since 2004) but offering higher data transfer speeds. PDD was not intended for home video use and was aimed at business data archiving and backup, although currently it is gaining popularity as a HD video format media and PlayStation 3 media. The UDO format is also aimed at similar purposes. Blu-ray is currently embroiled in a battle format war against the HD-DVD disc.