AAC,
MP3, WMA? What does it all mean? What's the difference? Why should you care? An article at theBaltimore Sun aims to sort out these questions and more, by explaining the difference between the three codecs and CDs, where each is used, and hardware compatibility of each. He also included an apology for a previous gaffe calling AAC a proprietary file format
Check It Out: The Baltimore Sun Sorts Out The Alphabet Soup Of Audio Codecs