A CD is an optical storage medium which stores music, text or data on its
surface, in the form of small holes called 'pits'. The laser beam from the CD
player, bounces off these pits, and the degree of the reflection of the laser
beam, is read as the "0" s and the "1"s which make up the the binary code which
is converted into the respective signals, whether music, data, or movies etc.,
depending on whether the CD is CD-Audio, CD-ROM, or a Video CD etc.
A CD can contain upto 79 minutes of music or about 800 MB of data and hence is
a convenient format for storing a large amount of information. As a music
carrier, an audio CD offers a very high degree of clarity of sound
reproduction, without the inherent noise from the medium, (like the tape hiss
or the crackle from an LP record). As for CD ROMs, one 650 MB CD ROM can hold
enough information which would otherwise take over 400 31/4" 1.44 MB floppy
discs. And given the fast access time, as compared to the 400 or so floppies,
the advantages really stand out.
