Heidi is a work of children's fiction published in 1881 by Swiss author Johanna Spyri, originally published in two parts as Heidi: Her Years of Wandering and Learning and Heidi: How She Used What She Learned. It is a novel about the events in the life of a young girl in her paternal grandfather's care in the Swiss Alps. It was written as a book "for children and those who love children" (as quoted from its subtitle).

Heidi is an orphaned girl initially raised by her maternal aunt Dete in Maienfeld, Switzerland after the early deaths of her parents, Tobias and Adelheid (Dete's brother-in-law and sister). When some people ask Dete to come to the city and be their maid, Dete takes 5-year-old Heidi to her paternal grandfather's house, up the mountain from the Dörfli ('small village' in Swiss German). He has been at odds with the villagers and embittered against God for years and lives in seclusion on the alm, which has earned him the nickname 'The Alm-Uncle'. He briefly resents Heidi's arrival, but the girl's evident intelligence and cheerful yet unaffected demeanor soon earn his genuine, if reserved, affection. Heidi enthusiastically befriends her new neighbors, young Peter the goatherd, his mother, Brigitte, and his blind maternal grandmother. With each season that passes, the mountaintop inhabitants grow more attached to Heidi.