WORM optical drives are backup storage and data retrieval devices for personal computers. One of the earliest WORM systems was introduced about 1985 by the Colorado-based company Information Storage, Inc. Unlike magnetic disk drives which utilize mechanically operated read/write heads, WORM drives employ laser beam optics to read and write disk information. The term WORM is an anagram for Write Once, Read Many--the method in which information on optical drives is used and the only type of drive available up until mid-1987. Since that time, Sony Corporation and other drive manufacturers have begun introducing erasable optical disks, which have now surpassed the non-erasable disks in popularity and usage.

Although optical disk drives are much more expensive and slower in operation than magnetic disks, their advantages are their extremely large capacities and increased security over magnetic disks, which are prone to erasures, crashes, etc. Optical disks can hold the equivalent of several hundred books, in a fraction of the space required by standard magnetic disks or tape storage systems. Optical drives are especially suited for information searches in huge databases where speed is not a particularly important consideration. As the drive technology advances, the speed and cost factors of optical drives can be expected to improve vastly.