Cakaram format optical storage for digital media, including high definition video. The name Blu-ray is taken from a laser color -purple-blue that is used to read and write discs of this type. Disc Blu-ray can store more data than the DVD format is more common because of the long wave-violet laser that is used only 405 nm, which is shorter than the red laser, 650 nm, used DVDs and CDs
