DIGITAL VERSATILE DISC, OR DVD

A DVD (which means Digital Versatile Disc or a Digital Video Disc) is an optical disc capable of storing up to 4.7 GB of data, more than six times what a CD can hold. DVDs are often used to store movies at better quality than a VHS. DVDs can also have interactive menus and bonus features such as deleted scenes and commentaries. Like CDs, DVDs are read with a laser.

The disc can have one or two sides, and one or two layers of data per side; the number of sides and layers determines how much it can hold. A 12 cm diameter disc may have one of the following storage capacities:

• DVD-5: single sided, single layer, 4.7 gigabytes (GB), or 4.38 gibibytes (GiB)

• DVD-9: single sided, double layer, 8.5 GB (7.92 GiB)

• DVD-10: double sided, single layer on both sides, 9.4 GB (8.75 GiB)

• DVD-14: double sided, double layer on one side, single layer on other, 13.3 GB (12.3 GiB)

• DVD-18: double sided, double layer on both sides, 17.1 GB (15.9 GiB)

There are also 8 cm DVDs with a storage capacity of 1.5 GB.

The capacity of a DVD-ROM can be visually determined by noting the number of data sides, and looking at the data side(s) of the disc. Double-layered sides are usually gold-colored, while single-layered sides are usually silver-colored, like a CD. One additional way to tell if a DVD contains one or two layers is to look at the center ring on the underside of the disc. If there are two barcodes, it is a dual layer disc. If there is one barcode, there is only one layer.