J.K. Rowling’s Harry Potter fan website was called Pottermore when it launched in 2011.
Pottermore was announced as an interactive digital experience built around the Harry Potter books. Rowling contributed new background material, including information about characters, magical institutions and wizarding history. The site also included interactive house sorting, wand selection and digital editions of the novels.
The public launch followed an earlier period of registration and testing. Pottermore later expanded beyond its original format and was relaunched as Wizarding World in 2019, combining Harry Potter and Fantastic Beasts material with news, quizzes and other features. That change explains why newer references may use Wizarding World rather than Pottermore.
Pottermore was also connected with the digital distribution of Harry Potter e-books and audiobooks. It was not a new novel and did not replace the original books; its main role was to provide an official online companion experience and additional Rowling-written text.