CD-Read Writable

What Does CD-Read Writable Mean?

CD–Read Writable (CD-RW) refers to an optical CD that may be written and rewritten multiple times. CD-RW allows for data erasing during each rewritable session. However, data cannot be changed during CD-RW sessions. Some CD-RW discs have a multisession feature, in which additional data may be written at a later time if extra space is available.


A CD-RW can hold data for several years if the disc is protected from direct sunlight. Most CD-RW discs hold approximately 74 minutes and 640 MB of data, but some hold 80 minutes and 700 MB of data. Experts claim that a CD-RW’s rewriting cycle may occur up to 1000 times.

The CD-RW term is also known as CD-Rewritable (CD-RW).

Techopedia Explains CD-Read Writable

Introduced in 1997, CD-RW followed the CD-Magneto Optical (CD-MO) format, which introduced the multisession writing standards via a magneto-optical CD recording layer. Although never commercially available, CD-MO was established in Part 1 of the Trusted Computer System Evaluation Criteria (Orange Book) of the Rainbow Series, which was originally released by the U.S. government department of defense (DoD) in 1990.

Most CD-RW discs have a multisession format feature capable of adding data during different sessions. Additionally, individual data files and directories may be deleted or updated as needed. This feature links one or more previous recorded (burned) sessions without consuming additional space, and subsequent recording sessions are linked to previous sessions. A CD-RW without the multisession format feature looks at the first session only and overwrites all of the disc data. Thus, most audio CD players cannot read written multisession data.


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Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.