Thouht I'd just express my opinion on the matter. If a song has been around for a while and survived, if it is sung and passed on by people who aren't the original writers and if it has at least the chance to change it's a folk song. Obviously people are going to argue about how long it should survive for and I have no doubt people will disagree with me but I think thats a decent definition. I think a lot of the hard core folk purists on this site would be shocked to realise what fits into that category. Certainly a lot of sixties and seventees stuff has survived for a generation or two. It's quite a bit older than me. In a lot of cases I learned it from family and friends of the family. There have been enough changed and forgotten words for the song to have changed at least a bit. The obsessive folkies on here probably won't like it, but when I've been at impromptu sessions with folk (not the "folk elite" or whatever with their siege mentality and their half hour conversations about the seventeenth verse of some ballad no one has wanted to sing in a century and more)it's been old rock and pop, even the odd bit of reggae that most people knew and joined in with. Now, at any impromptu sing around style event, there's a high probability of there being folkies around as well so I have no doubt that older songs will get sung, but eventually they will probably be forgotten and replaced with newer ones. That's natural. How many folk songs from the fifteenth or sixteenth centuries get sung now? How many EIGHTEENTH century songs have an unbroken line of performances up to the present day? There's no reason why desperado can't be a folk song if I sing it to my kids one day and they pick it up. If we lose all the traditional songs in twenty years that's terrible. If thirty year old ongs join the tradition and in seventy years time only the really great songs from the nineteenth or early twentieth centuries are being sung, I won't object.