I try to keep an open mind even if it's something I haven't experienced. Though I have had several experiences that weren't explainable, so yea I believe. Not in the typical 'ghost hunter' type of things, I've never really seen a full bodied scooby doo ghost or anything. Nothing so vivid that it had a definite face or shape with arms and legs. Blurs, movement, faint glowing.
It happened a lot as a kid with my family. I'd talk to my uncle who was dead before I was born. Cleaning out some junk one day my parents came across an odd tool, I was 4 at the time I think. And I mentioned 'oh a skate key'. The skates in my era didn't use keys, they did when my parents were kids. When they asked how I knew I said my (dead) uncle had told me, like what, doesn't everyone talk to him? More on the uncle, other people saw him too. Before I was born my mom had gone on lunch break at work, came back and her coworker told her that some guy had been in there looking for her. Said he was her brother. He passed when she was a teen so she was doubtful, asked the girl to describe him. She did, pretty well and mentioned he was dirty and greasy (he worked on cars a lot). My mom showed her a photo of him and she said yea, that's the guy. He'd died years earlier and someone who never met him had 'seen' him.
The typical stuff we had happen, the smell of burning hair in the shower out of nowhere. Bright orbs of light moving around the room. Ashtrays and things that were nowhere near the edge of the coffee table flying off like someone shoved them onto the floor. Unexplained noises from empty rooms (before bedrooms had tv's and things in them). Movement reflecting in the living room window as if a person walked by. Trying to duplicate it my mom had my dad walk outside past the window, looked wrong. Finally moved the couch away from the wall to walk between the couch and the wall it was butted against - bingo. Cold drafts with the air off, no fans running and windows closed.
Once had a cop at the house, my dad had left for work. It was a 2 story town house, the cop heard footsteps run across the floor upstairs. Asked who else was in the house, my mom told him no one. Had us stay downstairs, drew his gun and walked up to investigate. He checked the rooms, the bathroom, checked the closets. No one was upstairs. He came back down and looked at the ceiling where he heard the heavy footsteps and couldn't make sense of it. In order for the 'person' to have run across the way they did they'd have had to run through 2 solid walls.
Although around a week ago I was standing in the living room looking out the window at night. Lights were off so it was dark in there. Had gotten a glass of water. As I stood there I felt something shove the back of my leg, enough to cause my leg to buckle a little. Like someone had shoved the back of my leg behind my knee with their knee. Not something subtle like something brushing against me. Enough for me to turn around on the spot like 'what the hell?'. No one there. Wasn't a muscle spasm or anything, I clearly felt pressure shove the back of my leg forward.
No clue if it's ghosts, spirits, energy, who knows. All I know is I've seen weird shit over the years, stuff I couldn't explain. Just because it can't be explained doesn't mean it's not real, been pretty much the story of mankind. No one thought computer chips would exist a few hundred years ago. If you told people that 'invisible energy you can't see or touch' would be beaming moving pictures, sound, music etc into people's homes or to 'magic' handheld devices they carry they'd think you were batshit crazy. But now we do it every day with satellite, wifi, smart phones, smart watches. Not being able to measure it somehow doesn't mean it doesn't exist. I can't take a photo of a satellite signal with my camera. Back in the days of Lost in Space or Star Wars people likely enjoyed the 'scifi' aspect but called bullshit on laser guns. Yet just a few decades later Navy ships use directed energy weapons and can shoot planes or boats with lasers. The human body and senses are often limited, the inability to hear dog whistles or see UV light (during daylight, not black lights). So we're already constrained by a finite toolset with which to observe and try to use additional gadgets to make up for what we can't.