A Compact Disk holds 700 MB of data and natively plays PCM files, a compressed audio format. CDs are either R (Recordable) or RW (Re-Writable). A CD-R can be "burned" only once because of a physical perminant change that is imbedded in this disk via the laser. You can burn CD-RWs multiple times because the information is recorded in a shift in an ink coat that responds to the laser. However, because the ink shift is not as drastic as the physical change on a CD-R, some players will not play CD-RW disks.

A VCD is a Video Compact Disk that is a standard CD but an MPEG-1 video file has been burned onto it. These can be played in specific VCD and some DVD players.

see also Glass Master.