Do ghosts exist? Of course they do. Why else would tens of thousands of people from all nations around the world and all periods in human history report seeing them under more or less similar circumstances?
From historical accounts, it appears that the perception of ghosts occurs most often at night, in relative or complete darkness, or at least in some shadowed place, usually when the air is still. Certain localities are favorable for the appearance of ghosts -- why is difficult to determine. One theory has it that a ghost is a kind of psychic recording of an event in the past that took place at that locality, and that the locality acts as some sort of recording medium, and periodically replays the event under the right conditions.
Ghosts are often described as shadowy or translucent, certainly not like they are shown in the horror movies with eyes burning like coals and blood spurting or oozing from them!
Again there are a lot of experiences that I am sure you must have experienced must have left you flustered, at least I have. In some places, someone's home or some open area, for no reason, I have suddenly feltshivering with a chilly feeling down my spine and I have felt scared of being in those places again. Just an indicationof something unnatural existing in such places.