Blank CDs called CD-R (Compact Disc Recordable) platters can store data that has been transferred to them by a CD player. Since CD-Rs are frequently used to capture music, which can be played back by most CD devices, the term "recordable" is used. However, a CD-R can also be used to store a wide variety of other types of data, earning the discs the moniker "writable CDs."

As opposed to data stored on a hard drive, information etched onto a CD-R recording is irreversible and cannot be changed or deleted. Normally, a Disc can no longer capture data after it has been destroyed. Some CD burning software enables the recording of data as "sessions," enabling multiple complete writes to a disc. A computer will recognize a CD with multiple sessions as numerous discs because each session makes a new segment on the disc. On the other hand, CD-RWs allow for total deletion and re-recording. Like Discs, CD-RWs' data cannot be changed, so if you want to add new information, you must first fully delete the disc.