What MP3 quality is "CD Quality"?
In short, usually people are talking about 192kbps encoded MP3's when they say "CD Quality" (the higher the bitrate, the larger the file and usually the better the sound quality). However, what it really means to be "CD Quality" is somewhat more subjective.
Since MP3's use what is called lossy compression, it won't matter what bitrate you choose: you won't ever have a 1:1 copy of the orignal CD track (a 1:1 copy 5 minute song is about 50MB!). When an MP3 is made (or 'encoded'), some special tricks are used to make the music file smaller than the original 1:1 copy. When this done, the information that is lost isn't noticeable to a human listener if the bitrate is high enough. If a MP3 is created using a low bitrate, say 96kbps, you will be able to notice the loss of quality.
So the real question is: which bitrate sounds like CD quality?
And the answer to that is - for most people - 192kbps.
However, some sites use a different form of encoding called "Variable Bit-Rate" or VBR. Using this scheme, a MP3 is encoded using a bitrate that can dynamically change based on the content of the music. This provides a balance between CD quality and file size - which means you'll usually end up with a track that sounds the same as a 192kbps encoded file, but is smaller in size.