I don’t believe in ghosts personally, because as far as I know there is no scientifically validated evidence for them. If they do exist, I would have thought that some evidence would have been turned up for them. I think they may be some psychological or emotional effect.
I too do not think that ghosts are real, not in the sense that they are the spirits of dead people and we can talk to them.
I do think that there are some things that are unknown to science currently that we might think of as paranormal though. An example of this was ball lightning, which was something that you heard talked about in much the same way as UFOs and ghosts until it was seen in a laboratory.