What is the difference between CD and DVD disks?
DVD disks can hold many times the data that a CD can. CDs can hold around 650 megabytes (MB). DVDs can hold 4.7 gigabytes (GB) or about 4,700 MB. Put another way, DVD disks can hold about two hours of video. New technologies are pushing the capacities of DVD disks even further. Dual layer DVDs can hold roughly twice the data of a conventional single layer disk. Blu-ray disks, which are now being pushed by a number of manufacturers, can hold 27 GB in the single layer format and 50 GB in dual layer. A competing disk type, HD DVD, can hold around 15 GB. These newer standard DVD disks can only be used in drives designed to handle them.
