What is CD-RW?

The rewritable compact disc format is called CD-RW (Compact Disc Re-Writable). A rewritable Disc can be written to, deleted from, and then repeatedly written. Up to 80 minutes of digital music or 700 Megabytes of data can be stored on a single CD. Because the rewritable layer on the bottom of the disc is less shiny than the pressed layer on a CD-ROM, rewritable discs might not function properly in all CD players. A suitable disc reader with updating optical media capability is necessary to write to a CD-RW disc.

It is not possible to modify data that has been recorded to a CD-RW disc; instead, the disc must be deleted and rewritten in order to make any adjustments. The procedure makes the format a bad option for keeping data that need to be changed regularly. Rewritable discs, on the other hand, are better suitable for routine data backups, though that application is also constrained by the format's limited size in comparison to DVD±RW discs.

There are three lasers in an optical disc reader that can write discs: a low-power laser for reading data, a medium-power laser for wiping out rewritable discs, and a high-power laser for writing data to a disc. A phase change metal alloy mirrored coating on the bottom of the disc is burned with a sequence of dots by a CD-RW drive. This metal combination initially appears as a transparent crystalline structure. The metal is heated by a strong blazing laser until it melts, at which point it becomes opaque and cools. The scanning laser in the drive scans and decodes the digital data that is encoded in these dark areas. The medium-powered erase laser is used by the drive to heat the metal layer to the condensation point when it's time to delete a disc.

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