Ever experience supernatural encounter?where do they come from(GHOST)?

I have never experienced myself but heard lot of stories about them.....sometimes I feel like believing sometimes I dont

My sister told me this story that happened to her at her flat. Early one morning, her husband and she went to the mosque to pray. It was like about 6 in the morning. She went out of her house at about 5.30 am. Her daughter woke up at 6 and went to her room. She saw a shape underneath the blanket on the bed in my sister's room so she assumed her parents were still sleeping. She called out to her mother to wake up and heard a grunt so she left the room. My niece went on with the normal things she'd do in the morning - bath, brush her teeth and pray. Then she watched tv in the living room. At about 8 am, my sister and her husband came back. That's when my niece realized that what she saw in her parents' room wasn't her parents. Creeepy.