DVD 
digital versatile disc 
These high-capacity optical discs store everything from large computer applications to full-length movies. While similar in physical size and appearance to a compact disc or a CD-ROM, DVD is a huge leap from its predecessor's 650MB of storage. A standard single-layer, single-sided DVD can store 4.7GB of data. DVD also has a two-layer standard that boosts the single-sided capacity to 8.5GB. DVDs can be double-sided, ramping up the maximum storage on a single disc to 17GB. DVDs come in several formats, including DVD-video, DVD-ROM, DVD-RAM, DVD-A, DVD-R, DVD+R, DVD-RW, and DVD+RW. Not all drives read and write to all types of discs, but the emergence of multi-format DVD drives is eliminating the confusion.