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 used to read and write this type of disc. Because of its shorter wavelength, substantially more data can be stored on a Blu-ray Disc than on the standard DVD format, which uses a red laser.

What this does mean however is that a Blu-Ray disc will not play on a "standard" DVD player.

Can I play Blu-ray Disc on my existing DVD player?
No. To ensure playback you’ll need a dedicated Blu-ray player, Sony PlayStation 3 or a BD-Rom drive in your PC.

Can I play DVDs on a Blu-ray player?
Yes. Blu-ray players have been designed to be backwards compatible with regular DVDs so you can continue to enjoy your existing collection. In addition, Blu-ray equipment will allow upscaling of a DVD image up to a resolution 1080i/1080p for maximum visual quality.

Can I play Blu-ray Disc in a HD DVD player?
No. Blu-ray Discs are not compatible with HD DVD machines. Playback of Blu-ray Discs is limited to equipment bearing the Blu-ray Disc logo.

Do I need a new high definition TV to use Blu-ray Disc?
No. Pre-recorded Blu-ray Disc titles will play on any standard definition TV set, even if the video was encoded in High Definition.