you guys are giving him the dictionary definition of what MP3 is. i think what he wanted was to know how the copy protection and ID3v1 and ID3v2 tags are stored on an MP3 file.
winblowz i think all you need to know is to use an MP3 player/ editor like winamp. they can edit this data for you. there are 2 ways to edit the ID3: using CBBD to compare your MP3 to its own database and automatically fill in the ID3 with a known match OR the user must edit the info manually. note CBBD is sometimes free and it is not JUST for looking up info from audio CD's but MP3 also