CD-ROM (an abbreviation of "Compact Disc read-only memory") is a type of optical disk capable of storing large amounts of data. A single CD-ROM has the storage capacity of 700 floppy disks, enough memory to store about 300,000 text pages. All CD-ROMs conform to a standard size and format, so you can load any type of CD-ROM into any CD-ROM player. In addition, CD-ROM players are capable of playing audio CDs, which share the same technology. CD-ROMs are particularly well-suited to information that requires large storage capacity. This includes large software applications that support color, graphics, sound, and especially video.
source: Definition From the Webopedia Computer Dictionary