There’s more to experiencing a ghost than just seeing—in fact, the full-body apparition is just about the rarest form of ghost phenomena. There are several theories of what a ghost actually is: a person without a body, a recorded event that replays, a non-physical intelligence, or even a figment of the imagination. Most of the phenomena can be associated with any of those theories.
The most common phenomena are sounds and smells. For example, my husband and I, with our realtor, were inspecting a house after the seller moved out, before our closing. We were in the basement when we heard the floor (or ceiling, since it was coming from the main floor) creak in exactly the same way it would creak if a person entered the front door and walked through the living room and down the hallway.
I went upstairs; not only was there nobody in the empty house, the front door was locked, as was the back door and the patio door. I went back downstairs and both my husband and our realtor wondered who it was as both of them had heard the floor creaks, too. I felt kind of silly telling them it was a ghost; the house was two blocks from a cemetery.
I have a good friend whose father was a chain-smoker. She has never smoked, her husband has never smoked, and they live in a house that has never been the home of a smoker. Sometimes, one corner of a room will smell strongly of cigarette smoke. There is no logical explanation for the odor when and where it occurs. To her, of course, it’s simply her father stopping by for a quick visit.
Cold spots in an otherwise warm room or building are another common occurrence associated with ghosts. The theory is that an intelligent entity (such as a disembodied soul) requires energy to manifest, and the air temperature can provide that energy. This is also an explanation for fully charged batteries that suddenly drain to no charge in a matter of minutes or seconds. It doesn’t work very well for the recorded events theory, however.
Moving objects, such a s a hanging light that swings, can be caused by minor earthquakes, but if you have a row of them, say over a bar in a restaurant, and only one of them swings, it’s either a very odd tremor or something else. Other moving objects—light switches, faucets, power buttons—are also plausible ghost phenomena.
Some people believe very strongly in orbs, tiny balls of light that they claim show intelligence in their movement. I don’t buy it, because they look exactly like backlit dust close to a still or video camera lens; a video camera is going to show intelligent movement because of the intelligence behind the lens.
Then there are the very rare phenomena—disappearing/reappearing objects, shadow forms, partial apparitions, and full-body apparitions. Since they are rare, you want to use them sparingly.