Compact Disc-Re-Writable. One step above cd-r on the data-storage totem because you can re-write it, making the format useful for backups and mastering. However, CD-RWs offer a couple caveats, also, in their use outside of the computer world. When the discs are used for audio, most CD players are inable to read them -- "shallower" information, you see -- except for those in the most recent generation or so. Philips and other manufacturers have taken the added step of labeling their hardware as CD-RW Compatible.