What makes folk metal interesting is how it is the unlikely union of two things that should not go together. Metal is hard, brash, and abrasive, while folk music is soft, acoustic, and introspective. Folk would be at the bottom of the list of other genres I would expect metal to ever be paired with, given the fundamental differences between them, and yet there is a healthy and thriving scene of folk metal bands that have managed to forge a connection between the two styles.