Perhaps, ghosts can exist in the world. Because the human eye can only see a certain amount of things. So there may be ghosts exist in the world that humans can't see.
I know a girl who feel ghosts sometimes, she calls them "presence". Sometimes she heard or see them but, especially feels them. When she hears sounds in her garage, use some rosmery flowers, and says that they calm down. She says that usually are spirits from people that are lost or they still have something to do here, or are a guardian of some person. My grandmother is my guardian she say for example, other person say her.
I usually get scared over nothing because I always imagine ghosts watching me and all that. So I kind of believed it? Been expecting to see one for years and not once I got the chance, so it's always my imagination. That probably means I don't believe it that much
I have experienced lots of paranormal activity and seen many things I couldn’t explain. I without a doubt believe that there are ghosts/spirits out there to some capacity.