Noone answered my question are mp3's burnt cd's? Or what is an mp3? Because I understand that an mp3 is a burnt cd and some cd's will work and some won't. Mp3's came out along time ago like in 95 or something like that my 6 disc cd-changer in my car will play some cd's but not other's. Same with my brother's car and my friend's car they play burnt cd's just certain one's.