Ok, what do you think it is?
Bearded blokes in Aran jumpers singing long ballads with their fingers in their ears?
Intensely boring singers nasally whining away to cheap Japanese guitar accompaniment about the details of their love lives?
Vegetarian lasses with long plaited hair and Indian print frocks singing sweetly of murder and other devilish deeds?
Or simply loads of diddly-diddly-diddly a la Riverdance?
Well, maybe... Just a little bit... Sometimes...
But much much more, it's ...
Real voices singing with passion or sensitivity; instrumentalists - not just guitars, but concertinas, fiddles, mandolins, melodeons, bodhrans and even more exotic things. Have you ever seen a hurdy-gurdy or Northumbrian pipes or a cittern?
It's ordinary people expressing themselves, enjoying the experience of performance, striving to better themselves in an environment free of the "us and them" attitude of other art forms.
Professional and semi-professional guests show musical ability that is at least the equal of their pop, rock or country equivalents, arguably as good as those highly trained classical performers; they are often very knowledgeable and can tell of the background to their chosen material, yet essentially they are entertainers.
One of the best things about the Folk scene, though, is the way that amateurs and professionals share the same stage and mix sociably, for, in most cases, folk clubs are social clubs as much as concert venues.
Some will argue that real folk music is the tradition and the music should remain faithful to the old ways. More of us these days see folk as an on-going thing which modifies itself from generation to generation, reflecting the times, but always, always belonging to the people.