A cd-ripper is an application that copies audio from CD's into the computer without modifying the digital source. The ripper reads from the CD and saves the audio as .WAV files. It does not read the audio through the sound card. This is called Digital Audio Copy (DAE). When the audio-tracks are copied to the computer, one can either make perfect copies of the original audio-CD, or, convert the .WAV files into .MP3 files. If you would like to download some free MP3 music files I suggest you go check out Top 50 MP3 Download Sites.
To be able to use a cd-ripper, one need a good cd-drive. Not all drives can actually read digital audio. Some rippers though can read the audio using the cd-roms playfunction and then samples the audio. This will not make perfect copys and should only be used as the last alternative if nothing else works.