Blu-ray is a name for a optical disc standard which uses blue-violet laser instead of red laser used in CDs and in DVDs. This allows manufacturers to store more data using the same amount of disc surface.
In fact, Blu-ray got its name from the technology, basically the "Blu" is from blue-violet diode and the "ray" is from optical ray. The "e" was intentionally dropped so that the full term "Blu-ray" could be registered as a new trademark.
There were many developers and supporters of Blu-ray and it is important to note them. The founders of the technology is the Blu-ray Disc Association which now consists of 180 companies worldwide. The Board of Directors of the BDA are:
Apple Computer, Inc.
Hewlett Packard Company
LG Electronics Inc.
Matsushita Electric Industrial Co., Ltd.
Mitsubishi Electric Corporation
Royal Philips Electronics
Samsung Electronics Co., Ltd.
Sun Microsystems, Inc.
Twentieth Century Fox
Walt Disney Pictures
Warner Bros. Entertainment
There are a few formats of Blu-ray Discs available or in the works including BD-ROM, BD-R and BD-RE. Although HD DVD has had combo discs (one side HD, other side standard DVD), Blu-ray has not yet created such a format, but is planning to introduce it soon.
Videos will be stored on either MPEG-2 (enhanced for new HD), MPEG-4/AVC (High Profile standard) or on the best of all three, VC-1 (HD standard based on Microsoft's Windows Media Video (WMV) technology.)
One Blu-Ray disc will hold appx. 25GB of data (compared to 4.36GB on regular DVD) on one side/layer of the disc and 50GB on a dual-layer disc.
BD support many types of audio codecs as well with up to 8 channels of uncompressed audio. The codecs supported are:
Linear PCM (LPCM), Dolby Digital (DD), Dolby Digital Plus (DD+), Dolby TrueHD, DTS Digital Surround, DTS-HD High Resolution Audio and DTS-HD Master Audio.
In mid February 2008, Blu-ray became the victor in the next generation format war, when Toshiba decided to stop production on the rival HD DVD format. Before then HD DVD had proved to be a fierce competitor despite the fact that they had much less hardware sold in comparison to Sony and its Blu-ray including PlayStation 3.
For more information on how the format war ended check these news articles:
Toshiba confirms dropping of HD DVD (19 February 2008)
Warner speaks out about Blu-ray deal (11 January 2008)