The name Blu-ray is derived from the underlying technology, which utilizes a blue-voilet laser to read and write data, unlike the red laser which is used for CD’s and DVD’s. The E in Blu was removed for trademark purposes. The correct name is Blu-ray disc, not Blu-ray disk often shortened to BD.There are two sizes of BD. 25Gb and 50GB (dual layered) you can fit over 9 hours of high definition (HD) video onto a 50GB disc and over 23 hours of standard definition (SD) video.There are 3 main formats of Blu-ray.BD-Ram – read only format for HD movies, games etcBD-R - recordable format for HD video recording and data storage.BD-RE – rewritable format for HD video recording and PC data storage.Blu-ray is interactive you can consult menus wihtout stopping your film, you do not need an internet connections for basic playback of Blu-ray movies, however, it is needed for value added features such as downloading new extras, watching recent movie trailers and web browsing. It will also be required to authorize managed copies of Blu-ray moveies that can be tansfrerred over a home network. Blu-ray is backwardly compatible with DVD. Most Blu-ray players support upscaling of DVD’s to 1080p / 1080i so no-one has to worry about their old DVD favourites.Blu-ray disc provides the below key features and advantages.* Maximum picture resolution – Blu-ray disc deliveres full 1080p video resolution to provide pristing picture quality.* Best audio – as many as 7.1 channels of native, uncompressed surround sound for crystal clear audio.* Enhanced interactivity – Seamless menu navigation, new bonus feature and network/internet connectivity.There are 3 region codes for Blu-ray, the region code must be decided before the disc are authored .A – America, Korea, Japan and South East AsiaB – Europe, Middle Est, Africa, Australia and New ZealandC – Russia, India, China and the rest of the world