“In folklore and mythology, a ghost (sometimes known as a spectre, phantom, apparition, spirit, spook, or haunt) is the soul or spirit of a dead person or animal that can appear to the living. Descriptions of ghosts vary widely from an invisible presence to translucent or barely visible wispy shapes, to realistic, lifelike visions. The deliberate attempt to contact the spirit of a deceased person is known as necromancy, or in spiritism as a séance.
The belief in manifestations of the spirits of the dead is widespread, dating back to animism or ancestor worship in pre-literate cultures. Certain religious practices—funeral rites, exorcisms, and some practices of spiritualism and ritual magic—are specifically designed to rest the spirits of the dead. Ghosts are generally described as solitary, human-like essences that haunt particular locations, objects, or people they were associated with in life, though stories of ghostly armies and the ghosts of animals have also been recounted.”
In my opinion ghosts (dead people) do exist. They on occasion visit their loved ones to ensure their safety. This can be through thoughts or dreams. Demons however will not enter a house because of spiders (which they can’t abide) and always enter a person out in the open. Demons can project images within a person thereby making the person think they see a ghost also.