Ghosts are added around the school when people have "unfinished business" and want to continue their life. Ghosts can come back to haunt someone or someplace.
A ghost is the imprint of the soul of a once-living wizard or witch, and as such, a type of spirit. These fleshless spirits are either afraid of death or have some extraordinarily strong connection to the locations they haunt.
Ghosts are unable to have much physical influence. They are visible, and appear as a greyish-silver apparition of their former (living) selves. They pass through solid objects without damaging themselves or the material, but create disturbances in water, fire and air. The temperature drops in the immediate vicinity of a ghost. Their presence can also turn flames blue.[1]
Non-magic people cannot become ghosts, nor can they see ghosts clearly.
In some instances, animals may also become ghosts upon death.
Nature[1][]
- "Wizards can leave an imprint of themselves upon the earth, to walk palely where their living selves once trod... But very few wizards choose that path."
- —Sir Nicholas discussing ghosts with Harry Potter[src]
A ghost is the transparent, three-dimensional imprint of a deceased witch or wizard, which continues to exist in the mortal world. Muggles cannot come back as ghosts, and the wisest witches and wizards choose not to.[1] It is those with 'unfinished business', whether in the form of fear, guilt, regrets or overt attachment to the material world who refuse to move on to the next dimension.[1]As a result, ghosts know nothing about the afterlife and some later come to regret that they became ghosts instead of moving on.
Having chosen a feeble simulacrum of mortal life, ghosts are limited in what they can experience. No physical pleasure remains to them, and their knowledge and outlook remains at the level it had attained during life, so that old resentments (for instance, at having an incompletely severed neck) continue to rankle after several centuries.[1] For this reason, ghosts tend to be poor company, on the whole. They are especially disappointing on the one subject that fascinates most people: ghosts cannot return a very sensible answer on what it is like to die, because they have chosen an impoverished version of life instead.[1]
Depending on the conditions of the person's soul, they may not be able to return, as Tom Riddle's self-mutilated soul is trapped in limbo for eternity and cannot become a ghost.[3]
Abilities[2][]
In passing through a living creature, ghosts give the sensation of plunging into ice-cold water.[4] Ghosts also secrete ectoplasm over time in places that they frequent.[5] They also have the ability to "almost" taste food, which is amplified with the use of pungent, rotting food.[6]
In addition, ghosts are also weightless and may fly in any direction. Ghosts are also able to be moved by the currents of air and water.[7][8]Ghosts cannot be destroyed (as they are already dead), however, they may be petrified with the gaze of a Basilisk. This can be reversed by a Mandrake Restorative Draught, although the method of administration is unclear. Ghosts may also be repelled by magical light, and therefore will retreat from a Wand-Lighting Charm.[9][5] Ghosts can also be frightened and retreat from a Skurge Charm, which will also clean up any ectoplasm that they have precipitated.[5]
Ghosts are known for gravitating around a specific area, often the location of their death. In such a case, it is said that the ghost "haunts" that location. They appear to have a particular connection to that location, as it is apparently possible to bind them there magically.[10] It is possible that ghosts may be bound into a mirror, producing an item known as a haunted mirror.