When a life is snuffed out through a cause other than old age and natural ailments, the spirit lingers in the Mortal Realm rather than immediately entering the Spiritual World, as is its due. The incorporeal form attached to such a being is what is commonly referred to as a Ghost. A ghost is bound to the Mortal Realm for as long as the time it takes for his physical remains to return to dusts or ashes. During this period, although a ghost can no longer influence the material world in any way, it is generally free to wander the world and enjoy new sights. In fact, a ghost is at a greater advantage when doing so compared to average humans as it can travel at a faster speed.
From individuals done to death by violence, however, a different type of ghost forms. These are spirits confined to the site of their deaths until their time to enter the Spiritual World. In addition, they differ from average ghosts in that their memories can manifest in a way that are physically seen by humans, although these memories do not actually take on a corporeal form that allows human to interact with these memories. Furthermore, such manifestations occur quite rarely, as the memories of these ghosts have to be drawn out through a medium that acts as a focus for memory recall. In general, the only activity that these ghosts engage in is to wander aimlessly among the sites of their demise. As a result, they are generally known as the Restless Horde.
Furthermore, there are some among the Restless Horde that are bound to the Mortal Realm even after their remains are no more. These are called the Bound Ones. They are the individuals who died with an overwhelming sense that there is still something left unfulfilled in their lives. Thus, their spirits are barred from the Spiritual World until such times when they are reconciled with their fates, either through being satisfied that they have finally fulfilled that which is on their minds at the time of death, or losing all hopes in ever attaining whatever it was they desired in life. There is also a third possibility. As time goes on, a particular one among them might be driven mad by the failure to attain their goals and be doomed to forever being barred from the ultimate haven for spirits. Mortals should be very careful of items strewn around potential scenes of carnage, for these can house a Bound One who might be able to usurp the place of the spirit natural to a particular physical body. This is what is commonly known as possession.
~ an excerpt from Primer on the Spiritual World