A ghost is the soul or spirit of a deceased person or animal who can appear in visible form or other manifestation to the living. Descriptions of the apparition of ghosts vary widely: the mode of manifestation can range from an invisible presence to translucent or wispy shapes, to realistic, life-like visions.
Ghosts are also said to be the emotions of those who perished. It is said that when a person dies, the last emotions they ever felt takes shape and form and that itself becomes the ghost of the deceased person. Ultimately, this particular emotion is condemned to repeat itself time and time again, which would explain why ghosts would usually reenact their deaths and would have their last emotions centered on the last thing they saw in life.
Normally, a ghost will start out confused and disoriented before realizing they are dead. In some cases, a trauma of sudden death can be so great that a ghost will think that are still alive and continue in a routine from their lives, oblivious to the fact they are dead.
Ghosts are often bound to an object or a place, normally the building they died or lived in or the area they died at, as such their movements are restricted, but this isn't universal, and some very powerful ghosts can move over larger distances, but unless they can move what they're bound to, they can never be totally free. They are also sometimes bound to their bodies, unless their bodies have been put to rest.
An interesting attribute, is often ghosts bring more or other things from their lives, as well as their spirit. An object that is very closely linked to ghost during their life, or linked strongly to their death, are sometimes recreated for their ghosts. This is the reason why ghosts of cars, and ships exist.