A ghost is said to be the apparition of a deceased person, frequently similar in appearance to that person, and usually encountered in places she or he frequented, or in association with the person's former belongings. The word "ghost" may also refer to the spirit or soul of a deceased person, or to any spirit or demon.^[1][2][3] Ghosts are often associated with hauntings, which is, according to the Parapsychological Association, "the more or less regular occurrence of paranormal phenomena associated with a particular locality (especially a building) and usually attributed to the activities of a discarnate entity; the phenomena may include apparitions, poltergeist disturbances, cold drafts, sounds of footsteps and voices, and various odours."^[2]

Ghosts are a controversial anomalous phenomenon. According to a poll conducted in 2005 by the Gallup Organization, about 32% of Americans believe in the existence of ghosts.^[4] The term ghost has been replaced by apparition in parapsychology, because the word ghost is deemed insufficiently precise.

The belief in ghosts as souls of the departed is closely tied to the ancient concept of animism, which attributed souls to everything in nature, including human beings, animals, plants, rocks, etc. ^[6] As the nineteenth-century anthropologist James Frazer explained in his classic work, The Golden Bough, souls were seen as the creature within that animated the body:

"If a man lives and moves, it can only be because he has a little man or animal inside, who moves him. The animal inside the animal, the man inside the man, is the soul. And as the activity of an animal or man is explained by the presence of the soul, so the repose of sleep or death is explained by its absence; sleep or trance being the temporary, death being the permanent absence of the soul... "^[7]

Although the human soul was sometimes symbolically or literally depicted in ancient cultures as a bird or other animal, it was widely held that the soul was an exact reproduction of the body in every feature, even down to clothing the person wore. This is depicted in artwork from various ancient cultures, including such works as the Egyptian Book of the Dead, which shows deceased people in the afterlife appearing much as they did before death, including the style of dress.

Another widespread belief concerning ghosts is that they were composed of a misty, airy, or subtle material. Anthropologists speculate that this may also stem from early beliefs that ghosts were the person within the person, most noticeable in ancient cultures as a person's breath, which upon exhaling in colder climates appears visibly as a white mist.^[6] This belief may have also fostered the metaphorical meaning of "breath" in certain languages, such as the Latin spiritus and the Greek pneuma, which by analogy became extended to mean the soul. In the Bible, God is depicted as animating Adam with a breath.

One of the earliest known ghost "sightings" in the west took place in Athens, Greece.^[9] Pliny the Younger (c. 63 - 113 AD) described it in a letter to Licinius Sura: Athenodoros Cananites (c. 74 BC �?7 AD), a Stoic philosopher, decided to rent a large, Athenian house, to investigate widespread rumors that it was haunted. Athenodoros staked out at the house that night, and, sure enough, a disheveled, aged spectre, bound at feet and hands with rattling chains, eventually "appeared". The spirit then beckoned for Athenodoros to follow him; Athenodoros complied, but the ghost soon vanished. The philosopher marked the spot where the old man had disappeared, and, on the next day, advised the magistrates to dig there. The man's shackled bones were reportedly uncovered three years later. After a proper burial, the hauntings ceased.

Source: Wikepedia