Blu-ray, also called BD (Blu-ray disc), is an optical disc format that is the successor to the DVD format. It is backward compatible with the DVD and compact disc formats.[1]
A Blu-Ray disc can store a movie in high-definition format and can more generally store up to 25 gigabytes (single-layer) or 50 gigabytes (double-layer). The format derives its high encoding ability, as well as its name, from the use of a blue-violet laser, which has a shorter wavelength than the red laser used in earlier formats.