Blu-ray or Blu-ray Disc (BD) is a digital optical disc data storage format.It was designed to supersede the DVD format, in that it is capable of storing hours of video in high-definition (HDTV 720p and 1080p) and ultra high-definition resolution (2160p).DVD-Video discs were limited to a maximum resolution of 480p (NTSC, 720×480 pixels) or 576p (PAL, 720×576 pixels).Besides these hardware specifications, Blu-ray is associated with a set of multimedia formats.Afterwards, it continued to be developed until its official release on June 20, 2006, beginning the high definition optical disc format war, where Blu-ray Disc competed with the HD DVD format.
High-definition (HD) video may be stored on Blu-ray discs with up to 2160p resolution (3840×2160 pixels) and at up to 60 frames per second.
The plastic disc is 120 millimetres (4.7 in) in diameter and 1.2 millimetres (0.047 in) thick, the same size as DVDs and CDs.
Conventional or pre-BD-XL Blu-ray discs contain 25 GB per layer, with dual layer discs (50 GB) being the industry standard for feature-length video discs.
In March 2002 the forum approved a proposal, which was endorsed by Warner Bros. The proposal involved compressing HD video onto dual-layer standard DVD-9 discs.
In spite of this decision, however, the DVD Forum's Steering Committee announced in April that it was pursuing its own blue-laser high-definition video solution.