Harry Potter is a series of seven fantasy novels written by the British author J. K. Rowling. The books chronicle the adventures of the adolescent wizard Harry Potter and his best friends Ron Weasley and Hermione Granger, all of whom are students at Hogwarts School of Witchcraft and Wizardry. The main story arc concerns Harry's quandary involving the evil wizard Lord Voldemort, who killed Harry's parents in his quest to conquer the wizarding world and subjugate non-magical people (Muggles). Since the 30 June 1997 release of the first novel Harry Potter and the Philosopher's Stone, (retitled Harry Potter and the Sorcerer's Stone in the United States) the books have gained immense popularity, critical acclaim and commercial success worldwide. The series has also had some share of criticism, including concern for the increasingly dark tone. As of June 2008, the book series has sold more than 400 million copies and has been translated into 67 languages, and the last four books have consecutively set records as the fastest-selling books in history. A series of many genres, including fantasy and coming of age, it has many cultural meanings and references. According to Rowling, the main theme is death, although it is primarily considered to be a work of children's literature. There are also many other themes in the series, such as love and prejudice. English-language versions of the books are published by Bloomsbury in the United Kingdom, Scholastic Press in the United States, Allen & Unwin in Australia, and Raincoast Books in Canada. Through 2010, the first six books have been made into films by Warner Brothers; it is the highest grossing film series of all time. The seventh book has been made into two films which are planned to be released nearly eight months apart: Part I was released 19 November 2010 and the series finale is currently scheduled for release on 15 July 2011. The series also originated much tie-in merchandise, making the Harry Potter brand worth $24 billion