Digital music is abuzz with new offerings that range from pay-per-download stores to monthly subscription sites. With all the activity, come a few new music formats. Both Windows Media Audio (WMA) and Advanced Audio Coding (AAC) include copy protection that allow the publisher to define what you can do with the download. MP3 is a popular music format that does not include any copy protection. When you purchase digital music, a desktop player or a portable music player, be aware of which formats are supported; very few of the most popular products support all three formats.