Demon is a spiritual entity that has as many names as it does functions. Also called spirits, spirit guides, the watchers, familiar spirits, fallen angels, jin, ghosts and even aliens, demons are the original angels in Heaven created by God who defected against His throne for either coveting it or agreeing with Lucifer in his rebellion to God .
Demonic entities exist in a dimension where we cannot see them, but their actions and involvement is constantly present. Being someone who does not believe in a spiritual aspect of life leaves you wide open fo spiritual attack, which is just as real as anything else you can see or touch.
Do not ever, under any circumstances, attempt to talk to or interact with a demon. They have over 6,000 years of experience in tricking humans, and none of them are good. If you think you are speaking to a kind demon and you have found some sort of exception, get out of that communication right away.
Because no spirits of humans roam the Earth or are looking down at us in a state of death, demons take advantage of this and are the only ones that pose as dead relatives and people that appeal to your inate sense of comfort. Never ever attempt to communicate with a demon posing as a relative, or in any form for that matter. They are simply too skilled and crafty for humans to deal with, without there being some sort of unwanted consequense.
A demon can always, in every situation, be commanded away in the name of Jesus Christ.