any of a variety of information storage disks that are played or read using a laser
. Optical disks include compact discs
(CDs and CD-ROMs), laser discs (see videodisc
), and digital versatile discs
(or digital video discs; DVDs and DVD-ROMs). WORM [W
any] disks can be used to record data, but once data is recorded it cannot be altered except by obliterating the old version and storing the new version on a previously unused portion of the disk. Magneto-optical disks,
such as the rewritable optical disk and the recordable disk used with the Mini Disc player, have a special layer, as of barium ferrite, that can be magnetically polarized by a recording head when heated with a laser. Data or sound may be recorded to and erased from any portion of a magneto-optical disk multiple times.
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