CDRWs

CD-RW, or CD-ReWritable, is a type of compact disc designed for multiple write-erase cycles. It uses a phase-change recording layer composed of a chalcogenide alloy (commonly AgInSbTe) that can switch between crystalline and amorphous states when heated by a laser. Data are written by raising the laser power to crystallize small spots; erasing returns the spots to the amorphous state. Readout is by a conventional CD laser, with differences in reflectivity encoding the data. The discs have a nominal capacity of 700 MB, or about 80 minutes of audio, and are available in standard 120 mm diameter with 74 or 80 minute audio formats.

CD-RWs require a CD/DVD drive that can write to rewritable media; many modern drives support CD-RW, but some older or budget devices may not. Not all players or car stereos can read CD-RWs due to formatting or reflectivity differences; readability is more reliable on modern drives in data mode than in audio mode. Recording modes include Disc-At-Once and Track-At-Once, as well as packet writing that enables incremental data writes and file-system-friendly updates.

Lifespan: the writable layer is designed for roughly 1,000 to 10,000 write/erase cycles, depending on manufacturing quality and handling. Proper storage in a cool, dark, vertical position helps longevity; discs are susceptible to scratches and heat, which can cause data loss.

History and use: CD-RW discs were introduced in the late 1990s as a reusable alternative to CD-R. They found use in data backup, software distribution, and multimedia projects, but adoption declined as DVDs, USB flash drives, and cloud storage became common. They remain in use for niche archival tasks and situations where rewritable optical media is preferred.