What makes it a Folk Song?

Age, provenance, endurability, popularity?

As I may쳌fve stated in other threads, in my own opinion, a folk song is any song most ordinary people know & can join in with.

Some쳌fve these may be considered by some to be 쳌epop쳌f rather than folk

But for me, when singing so called 쳌efolk songs쳌f in public, scarcely anyone knows 쳌eem, but when I do stuff from the Eagles, Beatles, Stones, BeeGees, Drifters etc, everybody knows 쳌eem.

Lately a song, which has become popular round my way, is 쳌eBaby can I hold you쳌f [Tracy Chapman]

Ms. Chapman is designated as 쳌econtemporary folk쳌f, so does this mean all her popular compositions are 쳌efolk songs쳌f?

And continuing in the same vein, rock, blues, jazz etc songs and classical tunes in 쳌etuney쳌f sessions [Carolan etc] are all popular in 쳌efolk쳌f events, but are they folk or not?

Up to you?