[bob francais]

I am a little slow to understand how mp3 looses quality .I am not talking about thetrading pool, just in general. I have downloaded alot of music from different places in mp3 format and have them on a harddrive, If I copy them to a cd in the same mp3 format do I loose quality everytime or do I only loose quality if I convert them to another format? Can someone please explain? thank you.