Demons are a spirit that likes to seriously, physically harm the living. They are said that they can also harm the livings soul. Demons are the most dangerous paranormal phenomena. They are mostly known for scratching, choking, pushing, hitting, possessing the living and more. Sometimes it can be bad for your health.
For Paranormal Investigators: If you are a beginner and don't know how to handle the paranormal, than don't investigate places with demons, first. Investigate other places, before you go to places with demons, to get used to the paranormal.