Technology / Computers / Blu-ray: Also known as Blu-ray Disc. This is an optical disc format that was developed to enable recording, playback, and rewriting of high-definition (HD) video. This technology has a storage capacity far greater than that of traditional DVDs. A single-layer disc can hold up to 25GB while a dual-layer disc can hold up to 50GB. DVD disc technologies use a red laser to read and write data. Blu-ray uses a blue-violet laser (hence the name). The benefit of the blue-violet laser over the red laser is its ability to focus the laser spot with greater precision because of its shorter wavelength. A red laser's wavelength is 650nm while the Blu-ray's wavelength is 405nm.