CD-R stands for compact disk recordable. CD-R disks can best be thought of as write once disks. You can copy or burn to them once and cannot add any more data later. CD-RW stands for compact disk re-writable. Because CD-RWs are re-writable, you can copy some files to a disk today; add more files tomorrow; erase some of the files the day after tomorrow and write over existing files. DVD stands for stand digital video disk DVD-R stands for digital video recordable disk. Like the CD-R, a DVD-R is considered a write once disk. DVD-RW is a rewritable DVD and works much like a CD-RW disk.