If when you hear a verse from one song sung in another, and it makes you glad not mad, then you know what a folk song is.

If you get excited by hearing different lyrics sung to the same old tune, then you know what a folk song is.

If you get a little disgusted with McKinley Morganfield (Muddy Waters) claiming authorship of songs you know darn well existed in a dozen variation before he recorded them, then you know what a folk song is. Of course you forgive him because he's just as deserving of the royalties as anyone.

I still believe there are only two people who ever wrote folk songs: Trad I. Shunnal and A. Nony Mouse. Everything else is folkstyle until no one knows who wrote it anymore.