Optical Discs These discs use laser technology to store large quantities of data, including
sound and images, in a highly compact from. They are available for both PCs and large
computers. CD-ROM (compact disc read-only memory) for PCs is a 4.75-inch compact
disc that can store up to 660 megabytes. CD-ROM is read-only storage, but CD-RW
(CD-ReWritable) discs are rewritable. Digital video discs (DVDs) are optical discs the
same size as CD-ROMs but of even higher capacity, storing a minimum of 4.7 gigabytes of
data. DVDs are now the favored technology for storing video and large quantities of text,
graphics, and audio data, and rewritable (DVD-RW) discs are widely used in personal com-
puter systems.