Red Book defines the standard of CD-DA. This standard is the basic lines of the entire CD industry. Standards of other CDS are on the basis of this standard.
The audio CD is the disc that only contains audio signal. According to the Red Book; the audio files should be the signals with a PCM with a sample frequency of 44.1 KHZ and a sample value of 16 bit binary system. This file called WAV is a digit signal without compaction.