A file of this type uses compression to drastically shrink the size of an audio recording. The size of a file using this compression is generally only one-tenth the size of the original, uncompressed recording. This allows you to download an entire song in only a few minutes, compared with an hour or more to download an uncompressed file! After downloading the MP3 file, you can play it instantly, anytime you wish. With MP3, you can create custom play lists of your favorite songs.