"How to Train Your Dragon" is a popular animated film series based on the books by Cressida Cowell. The story follows a young Viking named Hiccup Horrendous Haddock III, who lives on the island of Berk, where dragons and Vikings are traditionally enemies. Hiccup befriends a dragon he names Toothless, discovering that dragons are not the fierce creatures everyone believes them to be. Throughout the series, Hiccup learns to understand and communicate with dragons, leading to a new era of peace between the Vikings and these mythical creatures. The films explore themes of friendship, bravery, and the importance of acceptance.