Media Today
The book was turned to a movie and every book in the series got its own movie
From all the fans of the Harry Potter series a website was created to explain the story more and to "get in touch with the wizard world"
After the success of the first book a entire series where made and sold so well that its popularity makes everyone know about it.
With all the creative new elements incorporated into the Harry Potter world J.K. Rowling wrote books to explain things in her books. She also created side books to go along with the history in Harry Potter.
Since Harry Potter has so many iconic symbols and items fans wanted to get some of them to wear around or for a collection so they made a website for all sorts of merchandise