I believe that people and events can leave an imprint on places. I'm not sure about
ghosts per se, but I did have an experience as a child:
I was sleeping and something woke me up. At the time, my bed was next to the door(the door was on the same wall my headboard was against). I looked up, and I thought I saw my mom(she wore a lot of white nightgowns at the time). I wasn't wearing my glasses, so all I really saw was a whitish person shaped blob. I assumed she had woke up to use the bathroom, and had stopped in to check on me. I raised my arms in the classic "hug me" pose, and waited. Nothing. I stayed like that for a little bit, but the white shape didn't move. By the time I had turned, put on my glasses, and turned back, the shape was gone. I ran into my parents' room, and my mother took me back to bed, explaining that it must have been the light from the window across the room reflecting on the wall. I accepted that explanation at the time, but after thinking about it later, that doesn't really fit. The light from the window reflected on the wall
behind my bed, not the wall next to it, and it wouldn't have disappeared so quickly(the light that came in was from the hospital on the next street over, not the moon or something). Plus, the shape seemed very 3 dimensional, and right next to the bed, not 3 feet away. I never saw it again, but if it was a ghost of some kind, maybe it realized it scared me and decided not to do it again?
Years later, several of my friends told me they got a weird vibe in the upstairs hallway(where the bedrooms - including mine - were). I hadn't told them about my experience.