When taking about Ghost, I think its better for a person to consider its physical appearance. In other words, the fact that I and majority of the people seek in the discussion of Ghost have never seen it. Ghost is just an unknown figure that people can imaged. One example is an experience I have had in my old apartment. In 2004, I lived in an old apartment which Paranormal Investigators declared there was Ghosts. I lived in this apartment because I had no job, and so I would not afford to pay for rent. However I did not experience any noise, feeling, or even odor for the three months I live there. So, like I said earlier, Ghost is just an unknown figure that people can imaged. For stance, one is able to see the shape of a Squirrel in the sky if he or she really want to see one.