Seriously, having given the matter a fair amount of thought in the last 24 hours, I think I am ready to offer my (admittedly highly personal and subjective) definition of folk song; since others have set the ball rolling and also to defend myself against the charges of dishonesty and cowardice implied by one or two recent posters. Before I proceed, let me reiterate...this is my personal and subjective view, not one I'm trying to impose on anybody else.

***

A folk song, to me, is a song with a strong (ie. readily hum-able) melody and intelligent lyrics, sang either with optional acoustic backing or unaccompanied. This may be a Traditional song (by which I mean an old song still widely sung and composed by somebody whose name is lost to posterity and thus credited to Trad); or it may be a song written by someone whose name is known and may be either dead or alive, however recent or otherwise. But the two most important identifying features of a folk song are a strong melody and intelligent lyrics.

***

For what it's worth, I think the above definition can reasonably be applied to MOST Traditional songs, SOME of the revival-era protest songs, and SOME post-Dylan confessional-songwriter-type songs. And arguably some from other genres too. Perhaps it is more helpful, then, to view "folk" more as an indicator of quality than as a genre classification.

(posted in a sincere effort to explain what I think folk music is, as requested by at least a couple of posters...NOT in an attempt to start World War Three!)