I was listening to someone today talk about how negative energy can affect your presence in a situation.  Here is a clear cut best way to describe it.  Lets say you are in a room and everyone looks at you negatively.  You have either entered the room with hostility or you have brought your negative energy to a neutral room.  Because many times the world is encompassed with neutrality, you have probably brought a room down with your negativity and therefore it has become hostile.  It is something you should think about next time you go somewhere.