The reality of ghosts is a controversial subject which divides believers and skeptics. The study of ghosts is both the subject of folklore and also, since the nineteenth century, of the investigations of parapsychologists, who have attempted to refine the vocabulary used in describing ghostly phenomena.

The name "Devil" derives from the Greek word diabolos, which means "slanderer" or "accuser". In mainstream Christianity, God and the Devil are usually portrayed as fighting over the souls of humans, with the Devil seeking to lure people away from God and into Sheol. The Devil commands a force of lesser evil spirits, commonly known as demons. The Hebrew Bible (or Old Testament) does not assign this level of personification to the devil; there, the Adversary (Ha-satan) is a servant of God whose job it is to test humankind.

The Devil is the title given to the supernatural being, who, in mainstream Christianity, Islam, and some other religions, is believed to be a powerful, evil entity and the tempter of humankind. The Devil is commonly associated with heretics, infidels, and other unbelievers.

A place in which ghosts are claimed to appear is described as haunted. A related phenomenon is the poltergeist, literally a 'noisy spirit' that manifests itself by moving and influencing objects, though a widespread view today is that these occurrences are either fraudulent or manifestations of the psychic energy of, particularly, adolescent girls. Phantom armies, ghost-animals, ghost trains and phantom ships have also been reported.

The reality of ghosts is a controversial subject which divides believers and skeptics. The study of ghosts is both the subject of folklore and also, since the nineteenth century, of the investigations of parapsychologists, who have attempted to refine the vocabulary used in describing ghostly phenomena. Summoning or exorcising the shades of the departed is an item of belief and religious practice for spiritualists and practitioners of ritual magic. Though some claims of ghostly phenomena are proven frauds others remain unexplained or are subject to conflicting explanations. So far no one explanation has gained universal acceptance.