There is only one file type that uses the .M3U8 extension:
UTF-8 M3U Playlist File
An M3U8 file is a playlist file used by various audio and video playback programs. It contains a path or URL to a media file or folder of media files, along with information about the playlist. M3U8 files use the same formatting as .M3U files, except the text stored in the files uses UTF-8 character encoding.
M3U8 files are often used for storing playlists that have song names in different languages. They may also contain references to online files for an Internet radio station.
M3U8 files are supported by a wide variety of media players, such as iTunes, Windows Media Player, and VLC media player. You can also open the M3U8 file with a text editor since the contents of the file are stored as text.
NOTE: Some M3U files may already use UTF-8 character encoding. However, M3U files may also use other character encoding standards. Therefore, the M3U8 extension is used to explicitly state that UTF-8 character encoding is used.
Updated: January 9, 2018