We have seen before that a ghost is the physical manifestation of a soul, spirit, life force, or life energy. Most people use this term to describe the visual appearance of a human being or creature that has died and passed on to the other side. A ghost is most often residual in nature -- it does not interact with our physical world.

There are many kinds of phenomenon that fall under the denomination of ghosts but as always with monsters, we have to make a clear distinction between the different categories and base ourselves on the following arbitrar criteria :
Some ghosts are the exact image of the person they were, others are only recognisable by their faces. Often just a blur of white light is present. Some are said to be solid, some are translucent, others only noticeable by a breath of warm air or a cold hand. A ghost may not appear at all, but be recognised by eerie sounds or moving objects. Other spirits such as poltergeists are said to cause mischief, ranging from spilt milk or tangled yarn to grave accidents, but never materialize visually to the eyes of the witness.