Paranormal is a term used to describe a whole range of phenomenon which the causes and mechanisms are apparently unexplainable by established scientific laws. The prefix ''Para'' means something out of the norm, the norm being here the scientific consensus of an era. A phenomena is qualified ''Paranormal'' when it seems to be unexplainable by known natural laws, letting then wide open the field for all kind of researches, interpretations, suppositions ect.
It is then not to be wondered why some consensus have been established in the ''Paranormal world'', between Ghost Hunters and believers from all kind of investigations and Paranormal studies made on the subject of ghost. Accounts of Paranormal activity are also important and allows patterns to be established and links to be made.
The issue is, something as popularized by millions of people gobally should be verified easily.
Other things once considered paranormal - bioluminescence etc. - are easily documented, verified, proven - and bioluminescent creatures were not witnessed by the masses worldwide.
See where I'm coming from?