Compact Disc definition storage
(CD) (Not "disk", this spelling is part of the standard).
A 4.72 inch disc developed by Sony and Philips
that can store, on the same disc, still and/or moving images in monochrome and/or color; stereo or two separate sound tracks integrated with and/or separate from the images; and digital program and information files.
The same fabrication process is used to make both audio CDs and CD-ROMs
for storing computer data, the only difference is in the device used to read the CD (the player or drive).
CD Information Center (http://cd-info.com/cd-info/CDInfoCenter.html).