It is a 2017 American supernatural horror film directed by Andy Muschietti and written by Chase Palmer, Cary Fukunaga, and Gary Dauberman. It is the first of a two-part adaptation of the 1986 novel of the same name by Stephen King, primarily covering the first chronological half of the book. It is the first film in the It film series as well as being the second adaptation following Tommy Lee Wallace's 1990 miniseries. The film stars Jaeden Lieberher and Bill Skarsgård as the lead roles, with Jeremy Ray Taylor, Sophia Lillis, Finn Wolfhard, Wyatt Oleff, Chosen Jacobs, Jack Dylan Grazer, Nicholas Hamilton, and Jackson Robert Scott featured in supporting roles. The film was produced by New Line Cinema, KatzSmith Productions, Lin Pictures, and Vertigo Entertainment. Set in Derry, Maine, the film tells the story of The Losers' Club, a group of seven outcast children who are terrorized by the eponymous being which emerges from the sewer (Skarsgård), only to face their own personal demons in the process.

Supernatural horror film is a film genre that combines aspects of supernatural film and horror film. Supernatural occurrences in such films often include ghosts and demons, and many supernatural horror films have elements of religion. Common themes in the genre are the afterlife, the Devil, and demonic possession. Not all supernatural horror films focus on religion, and they can have "more vivid and gruesome violence".