A playlist file can have various extensions depending on the media player or software being used. Some of the most common file extensions for playlist files are .m3u, .pls, .wpl, and .xspf. For example, Windows Media Player uses .wpl, iTunes uses .m3u and .pls, and VLC media player uses .xspf. It's important to note that different media players may accept different file extensions, so it's important to check the software's documentation for compatible file types.