The "Oz Books" are a series of children's novels originally created by author L. Frank Baum. The first book, titled "The Wonderful Wizard of Oz," was published in 1900 and follows the adventures of a young girl named Dorothy who is swept away to the magical land of Oz. The series features various characters, including the Scarecrow, Tin Man, and Cowardly Lion, who accompany Dorothy on her journey. Baum wrote 14 Oz books, and after his death, other authors continued the series. The stories have inspired numerous adaptations, including films, stage productions, and merchandise, making Oz a beloved part of children's literature and popular culture.