Whether or not you believe in them, the scientific investigation of ghosts is big business. Reality television shows that follow ghost hunters at work and the popularity of ghost tours in many U.S. cities prove that we are fascinated by the possibility that the dead may still be with us. This book examines evidence of the existence of ghosts and takes a critical look at what the scientific findings might actually mean. It also delves into the history of ghosts in cultures around the world and attempts to explain why the idea of being haunted by spirits of the dead continues to captivate us.