“Lyra and her daemon moved through the darkening Hall, taking care to keep to one side, out of sight of the kitchen” — so begins Philip Pullman’s novel The Golden Compass, the first of the His Dark Materials trilogy. With a new adaptation on HBO, His Dark Materials is drawing in new fans, while those who read the books when they were first published in the ‘90s are happily rediscovering them. Daemons are an integral part of the book — but what are they, exactly?