Blu-ray Discs (BD) are a digital optical disc data storage format. The discs were designed to supersede the DVD format, increasing the storage capacity, therefore allowing hours of video in high-definition and ultra-high-definition resolution to be stored. The main application of Blu-ray is for video material such as feature films and for the physical distribution of video games for games consoles.Blu-ray Disc TypesBlu-ray discs are a plastic disc 120 millimetres (4.7 in) in diameter and 1.2 millimetres (0.047 in) thick, the same size as DVDs and CDs. Blu-ray discs are available in different storage formats called layers, containing 25 GB per layer. Dual layer discs are the industry standard for feature-length video discs and contain 50 GB storage space. Triple-layer discs (100 GB) and quadruple-layer discs (128 GB) are available but require additional BD-XL re-writer drives.