Blu ray disc is the next generation optical disc format that was developed to enable recording and playback of high definition video hd as well as storing large amounts of data a single layer blu ray disc can hold 25gb which can be used to record over 2 hours of hdtv blu ray uses a blue violet laser to read and write data while current optical disc technologies such as dvd use a red laser the shorter wavelengths of the blu ray technology make it possible to record more data on the same sp