Haunted houses and those manifesting other paranormal activity often display phenomenon such as rapid temperature fluctuations, putrid smells with no visible source, knocking sounds on the walls and the unexplainable movement of household objects. About.com expert Stephen Wagner explains that apparitions and disembodied voices are also associated with haunted buildings. Inhabitants of haunted homes occasionally suffer physical harm such as scratches and bite marks.
Spirits that haunt buildings are ghosts, the souls of deceased people who have not moved on to the next dimension of their existence. The most famous type of ghost is the poltergeist, which frequently moves furniture and throws or levitates household objects. Other ghosts speak or write but do not manipulate material things.
Many people use the word "haunting" to refer to the presence of any supernatural being. This is inaccurate. True hauntings are caused exclusively by ghosts. Demonic activity often mimics ghostly behavior, but according to the Catholic Encyclopedia, it frequently and quickly escalates into frightening and potentially violent incidents.
There are three types of demonic activity: oppression, infestation and possession. Only infestation affects buildings and places rather than people. The New England Center for Psychic Research reveals that one of the most famous and controversial cases of supposed demonic infestation is known as the Amityville Horror, in which a house where multiple murders occurred terrified its new occupants with apparitions, smells, insect swarms and physical violence.