Although ghosts and apparitions have been reported for thousands of years,
surprisingly little information is available with regard to their nature or essence.
Ghosts are elusive and unpredictable, and the ways in which they manifest
are surprisingly diverse. Contrary to popular belief, most ghostly encounters
are not visual, but rather consist of noises, smells, sensations, voices, cold
spots, electrical disturbances such as lights switching off or on, and
displacement or movement of objects. Much of the available data is anecdotal
and is therefore prone to exaggeration, embellishment, and sometimes
outright deceit.