The compact disc (CD), as a standardized information carrier, has become one of the most successful consumer products ever marketed. Although the original disc was intended for audio playback, its specific advantages quickly opened the way for various computer applications. The standardization of the compact disc read-only memory (CD-ROM) and all succeeding similar products, like compact disc interactive (CD-i), photo and video CD, CD recordable (CD-R), and CD rewritable (CD-RW), has substantially enlarged the range of possible applications. The plastic disc has always represented a removable medium of large storage capacity. The advent of the personal computer, accompanied by the increasing demand for both data distribution and exchange, has strongly marked the evolution of the CD-ROM drive. The number of sold CD-ROM units exceeded 60 million in 1997.