CD-RW

Compact disc on which data can be recorded (compare with CD-ROM, compact disc read-only memory); unlike CD-R disks, stored data can be erased and CD-RW disks reused.

CD-RW drives can read CD-ROM disks but CD-RW disks cannot be read in all CD-ROM drives, although those that cannot read CD-RW tend to be the older types of CD-ROM drive as new drives can cope with CD-RW as standard.

Data is recorded onto a CD-RW disk by changing the properties of a special metal alloy at points corresponding to the pits on a CD-ROM. This change is made by a laser operating at its highest power. By pointing the laser at the same spot, but on medium power, the properties of the metal alloy revert to their original state, and the data is effectively erased. The data can be read because the laser-affected points of the alloy reflect light much less well than the parts of the alloy not changed by the laser.