Media type Optical disc Capacity ~4.7 GB (single-sided single-layer), ~8.54 GB (single-sided double-layer) Read mechanism 650 nm laser, 10.5 Mbit/s (1?) Write mechanism 10.5 Mbit/s (1?) Usage Data storage, video, audio, games DVD (also known as "Digital Versatile Disc" or "Digital Video Disc" - see Etymology) is a popular optical disc storage media format. Its main uses are video and data storage. Most DVDs are of the same dimensions as compact discs (CDs) but store more than six times as much data. Variations of the term DVD often describe the way data is stored on the discs: DVD-ROM has data which can only be read and not written, DVD-R and DVD+R can be written once and then function as a DVD-ROM, and DVD-RAM, DVD-RW, or DVD+RW hold data that can be erased and thus re-written multiple times. The wavelength used by standard DVD lasers is 650 nm[1], and thus has a red color. DVD-Video and DVD-Audio discs respectively refer to properly formatted and structured video and audio content. Other types of DVDs, including those with video content, may be referred to as DVD-Data discs. As next generation High definition optical formats also use a disc identical in some aspects yet more advanced than a DVD, such as Blu-ray Disc, the original DVD is often given the retronym SD DVD (for standard definition).[2][3]