Until some time ago, you had CD ROM drives that were only capable of reading CDs. That means the data once stored could not be changed or erased by the CD ROM drive. This limitation is now overcome by CD RW disk drives. RW in CD RW Disk Drive stands for Rewritable. With this technology the rewritable CDs can be treated just like a floppy disk or a hard disk, and data can be written once, or over and over again depending upon the kind of CD-Recordable media used.