This article is from the CD-Recordable FAQ, by Andy McFadden (firstname.lastname@example.org) with numerous contributions by others.
CD-R is short for "CD-Recordable". Recordable CDs are WORM (Write Once,
Read Multiple) media that work just like standard CDs. The advantage of
CD-R over other types of optical media is that you can use the discs with a
standard CD player. The disadvantage is that you can't reuse a disc.
A related technology called CD-Rewritable (CD-RW) allows you to erase
discs and reuse them, but the CD-RW media doesn't work in all players.
CD-Rewritable drives are able to write both CD-R and CD-RW discs.
All CD recorders can read CDs and CD-ROMs, just like a standard CD-ROM