"하이디" (Heidi) is a beloved children's novel written by Swiss author Johanna Spyri in 1880. The story follows a young girl named Heidi who is sent to live with her grandfather in the Swiss Alps. The novel explores themes of nature, friendship, and the importance of family. Heidi's adventures include befriending a boy named Peter and helping her sick friend Clara. The book has been adapted into various films, television series, and stage productions, making Heidi a timeless character in children's literature. The story highlights the beauty of the Swiss landscape and the simplicity of rural life.