They say the simple questions are the hardest, so...........

What is a demon ?
How do you know this?

[matthew321]

Well you know what the hard questions are. Okay this will take some thinking...

A demon is a word, used to describe a being or state of being. To know that these states of being or beings can be defined with the word demon is more difficult. (it is hard to define where demon should be applied)
The word has been nulled down but all uses are still a state of being, or a type of being. Demons are thought of as rebels (they don't follow the rules). This is true in the bible as well when god cast his angels from heaven for rebelling. They became demons for this rebellion. Here is a common term I hear: "I am a lead foot when I drive, I am a speed demon." (demon used as state of being and it is describing being rebellious to the speed limit laws)
Demon can also be used to describe malicious intent. So for example a man kills 100 people in cold blood. He did it just for fun. He could be described as a demon. This act was malicious and the term demon is describing a state of being.
Now a demon used as describing a being. They are thought to be angels who rebelled from heaven and went to hell. They became demons for this. Okay so they are now against god who is projected as perfect and good. So if these demons are going against good they are being opposites. That makes them "evil" or not good. That is a reason why they are not thought of as good. When the angels were thrown out of heaven they lost their angelic radiance. They lost the feathers and their wings became flesh. They went from being bright to dark. A complete opposite of their previous form.

Okay I will finish this tomorrow but I believe I may be off to a good start.

[rave phillaphia]

.... this is like trying to define religion. There is no definant answer but I guess we could put it broadly and say it is a negative entity that opposes the human race? or whatever is good? This is why I hate definitions and categories for such broad subjects.

[Tronth]

Well you have to think of the roots of the word demon. Demon is translated form the Greek term daemon which means all non human spirits outside of the realm of humanity. so technically speaking the word demon means- angel, demon, and any other non human spirit. just some food for thought... hope this helps

[matthew321]

okay part 2 of my post. It took longer then a day but that was due to laziness. I am rather ashamed of it.

The angels being demons now were against god. They were against many things god had done. Their main problem with god is that he made humans. Then told the angels they have to serve the humans. But these humans were considered lesser so some angels did not obey god.  So for not serving humans god kicked these angels out of heaven.
The angels became more dark and less beautiful. They have to go to a less radiant home (hell). In this home they contemplate things. How to destroy the creation (humans) that god them here in the first place. How to make them suffer, make god see the error of their creation.

This is why these demons seem to have such animosity toward humans and god. It really boils down to that they disagree. They are using their free will in the opposite manner of angels. When humans hear this story and get helped by angels, they think angels good and demons bad. Some people do get tortured by demons and those stories make demons look more evil. It also gives validity to demons not liking humans.
Eventually people get the idea that stay close to angels and to god. That way you stay away from demons. But these people seem to be the ones targeted the most.
 

The bible defines demons as angels who got kicked out of heaven. I would not keep it that simple. I think a demon is a word, an adjective and a noun. Simply used to describe state of being or a type of being. Simply a word used to describe rebellion which has been tied to become evil. That is what I think.

Thanks to those that replied so far.

Next questions how do they manifest/appear?
How do they interact with us?
what effects do they have?

[RunningElk]

Manifestation Of Demons Would Be Negative Energy (Duh) Interaction Would Be Anything Really From Idle Chatter To Deals To Just Messing With Everyone To Possession And Effects Would Be Creation Of Material Out Of Pure Energy Eg. That Latest Xbox Console, Fire Balls Practically Anything For One Thing Negative Energy But As Pointed Out By Matthew Most Demons Are Here To Make Our Life A Living Hell (no pun intended)

I have a theory (I'm sure other people may think this way too) that what people call demons (not all, but some) are angels that have the task of "scaring" humans closer to God. This is just a theory and even I don't believe this 100% but I have a friend who was previously basically agnostic who had a very terrible experience with some demons. Afterwards she became Christian without influence from the others who witnessed the incident. This led us to the theory previously stated. It sort of make sense for some cases. Just thought I'd share!

I do believe that they can take any form or shape they want to. 

Don't think that they interact with us but more influence our thinking and through that effect us. They feed on our fears and emotions.

[Tronth]

I dont think a demon is manifested I think they are drawn by something, that something being greed, sex, energy or just curiosity. I also dont think demons do anything a human wants unless it knows it has something to gain from it. But that is just my belief.

I do believe that they can take any form or shape they want to. 

Don't think that they interact with us but more influence our thinking and through that effect us. They feed on our fears and emotions.

What about the many possession stories of the Bible - people going insane, diseases, blindness etc. Not only Biblical times but after 1900's many reports surfaced about men of God casting out demons from possessed people. I, also, had a run - in with a spirit/demon.  What he got was kicked out.
Yes they influence our thought and actions. That is their job. The "devil" didn't make anybody do anything unless they are possessed.

I do believe that they can take any form or shape they want to. 

Don't think that they interact with us but more influence our thinking and through that effect us. They feed on our fears and emotions.

The "devil" didn't make anybody do anything unless they are possessed.

What do you consider possessed?
There are different influences: Ordinary activity which is temptation
                                                 Extraordinary activity:  External physical pain

                                                                                      Demonic possession, diabolical oppression,diabolic obsession, diabolic infestation and diabolical subjugation or dependence.

[cylinder2166]

The description on demons here is better than some of my books, was their something more specific you needed to know?

I'm pointing our that throughout history there are are many reports of possession and because of this possession the entity has seriously interacted with humans.
Rosemary Guiley, Demons & Demonology, p.198 " possession - The takeover and control of a person's mind and body by a Demon, condemned soul, ghost, spirit, or deity. ....In demonic possession, a demon takes up residence in a person's body and influences or controls his or her thoughts, words, and actions. "
The possession has 3 stages - infestation, oppression, Possession.  Even mediums and channelers are voluntarily taken over by an entity for a time.

A demon is a kind of defination on one people being a demon but the main meaning of it(based on what i thought) not a spirit but a people doing things against god an his rules like killing