Blu-ray Disc (BD) is a digital optical disk data storage format. It was designed to supersede the DVD format, which is capable of storing high-definition video resolution (1080p). While DVD supports Standard Definition Video. The common blu-ray disc is 120 mm in diameter and 1.2 mm thick, the same size as DVDs and CDs.
Conventional (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. Triple layer discs (100 GB) and quadruple layers (128 GB) are available for BD-XL re-writer drives.