DVD, also known as "Digital Versatile Disc" or "Digital Video Disc," is an optical disc storage media format. Its main uses are video and data storage. 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 (Read Only Memory) has data that can only be read and not written; DVD-R and DVD+R can record data only once, and then function as a DVD-ROM; DVD-RW, DVD+RW, and DVD-RAM can both record and erase data multiple times. The wavelength used by standard DVD lasers is 650 nm; thus, the light has a red color.
DVD Video and DVD Audio discs refer to properly formatted and structured video and audio content, respectively. Other types of DVDs, including those with video content, may be referred to as DVD Data discs.
As next-generation High Definition optical formats (such as Blu-ray Disc and the defunct HD DVD) have been developed, the original DVD is occasionally given the retronym SD DVD (for standard definition).