HD-DVD (High-Density Digital Versatile Disc) is a digital optical media format which is being developed as one standard for high-definition DVD. HD-DVD is similar to the competing Blu-ray Disc, which also uses the same CD sized (120 mm diameter) optical data storage media and 405 nm wavelength blue laser. HD-DVD is promoted by Toshiba, NEC, and Sanyo, and backed by four major film studios.
HD-DVD has a single layer capacity of 15 GB and a dual-layer capacity of 30 GB. Toshiba has announced a triple-layer disc is in development, which would offer 45GB of storage.