Compact disks. Abstract computer artwork of compact disks (CD's). Images, sound and computer data can all be stored on compact disks. This information is coded digitally as zeroes and ones (binary digits), and can be stored as multimedia on CD-ROM (Compact Disk Read-Only Memory). A compact disk is made of plastic pressed with a series of fine depressions that represent digitised signals of coded information capable of being read by laser. The encoded layer is coated with a film of metal to reflect laser light. CD's have a large data storage capacity. Images, sound and text on multimedia disks can be accessed at random.