Paranormal, supernatural?

Are they just misinterpretations of natural phenomenon or do they have a solid chapter of existence in this world? (e.g. A ghost is really a ghost, supernatural beings, demonic possessions, seers…)
I've never experienced anything like it, so it's hard for me to believe in such things. Though I have heard stories from family members, and they sound like something that would make me a believer if I had experienced them myself.
Any experiences that made you a believer?
Added (1). In one of the stories I've heard, two family members experienced the same thing at the same moment. Though one of them didn't recollect it until he was an adult. He was still in diapers when he went through the experience. He experienced it as a baby, and suddenly recalled that it happened one day as an adult. When he told my mother about it, she was surprised that he remembered it, because she hadn't told him about it happening. I'll leave it at that. Any other thoughts?

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