Ghosts and spirit are controversial phenomena which have several possible definitions:
The spirit or soul of a person who has died, especially one which haunts a place which was of emotional significance to that person when living.
The personality of a person after his or her own death which is not directly tied to the soul or spirit. A sort of psychic memory-imprint.
The character or memory of some being or thing which has died or, if it was never alive, been somehow destroyed or disassembled, which nevertheless remains existent (and sometimes detectable) in a semi-corporeal form.
According to reported sightings, ghosts have taken the shape of birds,humans, animals, and even vehicles. There are reports of ghosts (usually of deceased humans) in most cultures throughout the world. There is a great deal of dispute whether ghosts are figments of the imagination or part of objective existence. Ghosts are among the subjects studied by parapsychologists.