May I quote Brian Peters (without permission, but I'm sure he won't mind), writing in the current (Spring 2000) issue of South Riding Network: Folk News?

"...I attempt no definition at all beyond a subjective one of what interests me personally,which ... is the body of old songs and tunes that have been around for centuries, for a significant part of their existence communicated orally. They are full of the most glorious and often strange melodies, wonderfully poetic and timeless lyrics dealing with anything from the mundane to matters of the utmost darkness and mystery. They are different and weird ... no software program will ever reproduce them, but they can arouse emotions and speak to parts of us that we'd almost forgotten we had. And they are ours."

I couldn't put it half so well myself, but I agree wholeheartedly.