ALBW (AlbumWrap) is a file format for storing a complete album which may be broken down into individual files for each of the album's tracks. Files of this format are usually identifiable as such since their names typically contain a "_ALBW" identifier. This format is popular on file-sharing networks such as eDonkey and Overnet. Whether or not ALBW files are playable in their unextracted form, as a regular MP3, this author does not know. But, if you know the answer to that, update this bloody Wikipedia article.