A haunted is a location or individual afflicted with the spirit of a deceased person or animal. A ghostly presence is often associated with a past traumatic event, typically a violent death or unresolved grief. The haunting may also be the result of a spell or dabbling in black magic (like what happened to the house of Dracula).
There are many things a ghost can do to disturb its living host. Some of the more traditional visual manifestations are apparitions, disembodied footsteps and a sudden appearance of strange lights. Sounds may include disembodied voices, screams or laughter. Other signs of a haunting are the sudden emanation of sounds from musical instruments and the spontaneous movement of objects.
When the ghosts are ill-intent, their actions are likely to cause physical, emotional and psychological distress. In this way, they can create fear or paranoia in the people around them. The more a ghost can evoke emotions in its living hosts, the stronger the effect of the ghostly presence.
Another way ghosts can scare us is by making the present feel insecure or unsatisfactory. They also tend to manifest in times of upheaval or loss, like when a loved one dies and is not mourned properly.
If you want to write a scary ghost story, start by thinking about the setting. There are plenty of creepy places to choose from, such as an old castle, a dark house, a graveyard or even a deserted island. However, you should avoid the obvious cliches and instead pick an unusual place that is both familiar and unfamiliar to your readers. This will make the story more believable and a lot more scary.