Residual Hauntings
"residual hauntings," these are by far the most common. Residual hauntings can be visual, audio, olfactory, or tactile. That is, they can be seen, heard, smelled or felt. A residual haunting can be described as the "imprint" of energy from another time, usually on a place, but sometimes associated with an object. In this type of haunting, the specter is not aware of anyone around him, and cannot interact or communicate with anyone. It is more like the re-playing of a tape or film, and it happens usually in the exact same way, over and over. It is thought that the energy produced by the person or people, when alive, during a time of high emotion or trauma somehow imprints itself on its surroundings and "re-plays" over and over again, even though the original participants are long dead. Such hauntings can be dormant for long periods and then triggered by a variety of things. A new family moving into an empty house, for example, or sometimes something as ordinary as a weather pattern can act as a trigger.
Poltergeists: A Specific Type of Residual Haunting
sub-category of residual hauntings would include poltergeist activity, considered by many not to be hauntings at all, as they do not appear to be related to any human spirit in particular. Rather, a poltergeist event seems to be a mis-direction of powerful energy, often destructive, and many times channeled through a living person. It is unknown what causes poltergeists to manifest in response to any one human being, but for some reason, this most commonly occurs with pre-teen or young teen-aged girls.
Intelligent Hauntings
Also called "active" hauntings, these can be very frightening, though the entity rarely means any harm to the living. An intelligent haunting involves a spirit who is intentionally present and sometimes even attempts to communicate with the living. Sometimes the spirit is not aware that they have passed, other times they do know, but are driven to bring some message to the living. Intelligent hauntings can include the sighting of an apparition, hearing a voice, or sometimes being aware of communication without any sound from the spirit. Usually, the apparition will be seen as they were in life, and wearing the clothing they would have worn, but occasionally they appear in the clothing their dead bodies were dressed in, or with wounds that may have caused their death. At times these ghostly figures will appear translucent or transparent, other times they look quite solid and real.
The Doppelganger
The subset of intelligent hauntings is relatively rare, but happens often enough to have been documented in a wide variety of cases, including some which have appeared to some very famous people, It is called a "doppelganger" haunting. Doppelganger means "double walker" in German, and is a phenomenon that involves someone seeing an exact double of themselves, almost always even dressed in the exact same clothing as they have on. Normally it will appear only to that person, while others around them are unable to see it, and tends to signify that something traumatic or tragic is about to happen to the person who sees him or herself.
Demonic Hauntings
Demons are described as evil energy from an unknown source that is unrelated to the human form. Many believe demons to be sent by the devil, but even non-believers have experienced demonic hauntings. Demons can appear as frightening looking animals, horrific and hideous creatures, or sometimes a black smoke or fog. They seem to be able to change shape and form, sometimes right before an observer's eyes, and their task is to wreak havoc in a subject's life, at times even possessing their bodies. Demons are thought to emerge from "gateways" near to where the haunting occurs. A gateway can be a cave, a well, a hole, or some other portal type entrance, usually from the ground. Another way for demons to infest a home or person can be through paranormal practices, such as dabbling in the black arts, attempting to cast spells, or using a Ouija board to try to contact spirits.
Shadow Hauntings
A sub-category of demonic hauntings is called a shadow haunting or shadow people. Shadow hauntings are often described as a shapeless form of dark mist, smoke or steam, and are usually seen in the peripheral vision. People who have reported a shadow haunting say that a feeling of foreboding or dread accompanies their appearance. Shadow people are similarly dark and filmy, but have no facial features or clothing, with the odd exception of a hat or hood. One type of shadow person appears with a hat similar to a fedora, and another type wears a hood. Shadow animals have also been reported, mostly in the rough shape of a cat.