Harry Potter is a series of seven fantasy novels written by British author J. K. Rowling. The novels chronicle the life of a young wizard, Harry Potter, and his friends Hermione Granger and Ron Weasley, all of whom are students at Hogwarts School of Witchcraft and Wizardry. The main story arc concerns Harry's struggle against Lord Voldemort, the Dark wizard who intends to become immortal, overthrow the Ministry of Magic, subjugate non-magic people and destroy anyone who stands in his way.
Since the release of the first novel, Harry Potter and the Philosopher's Stone, on 30 June 1997, the books have gained immense popularity, critical acclaim and commercial success worldwide. They attracted a wide adult audience, and have remained one of the preeminent cornerstones of young adult literature. The series has also had some share of criticism, including concern about the increasingly dark tone as the series progressed, as well as the often gruesome and graphic violence depicted in the series. As of July 2013, the books have sold more than 450 million copies worldwide, making the series the best-selling book series in history, and have been translated into seventy three languages. The last four books consecutively set records as the fastest-selling books in history, with the final instalment selling roughly eleven million copies in the United States within twenty four hours of its release.
The novels revolve around Harry Potter, an orphan who discovers at the age of eleven that he is a wizard, living within the ordinary world of non-magical, or Muggle, people. His ability is inborn and such children are invited to attend a school that teaches the necessary skills to succeed in the wizarding world. Harry becomes a student at Hogwarts School of Witchcraft and Wizardry and it is here where most of the novels' events take place. As Harry develops through his adolescence, he learns to overcome the problems that face him: magical, social and emotional, including ordinary teenage challenges such as friendships and exams, and the greater test of preparing himself for the confrontation that lies ahead.
Each book chronicles one year in Harry's life with the main narrative being set in the years 1991–98. The books also contain many flashbacks, which are frequently experienced by Harry viewing the memories of other characters in a device called a Pensieve.
The environment Rowling created is completely separate from reality yet intimately connected to it. While the fantasy land of Narnia is an alternative universe and the Lord of the Rings' Middle-earth a mythic past, the wizarding world of Harry Potter exists in parallel within the real world and contains magical versions of the ordinary elements of everyday life. Many of its institutions and locations are recognisable, such as London. It comprises a fragmented collection of overlooked hidden streets, ancient pubs, lonely country manors and secluded castles that remain invisible to the Muggle population.