A DVD or Digital Video Disc, since renamed Digital Versatile Disc, is a circular shaped plastic disc used for playing video, and storing data. Data is read by reflecting a concentrated laser beam at a thin metallic layer within the disc. Fine holes or pits in the layer are picked up by the laser mechanism, and converted into data or video.
A DVD uses the same concepts as a CD-ROM, but with higher speeds, and larger data storage, without increasing the physical disc size. The DVD format was designed to be backward compatible with the CD format.
A standard sized writable DVD stores approximately 4,700MB (4.7GB) of uncompressed data.