Previously unpublished Harry Potter material will be released on a new website in a move described by author JK Rowling as a "give-back" to her millions of fans.
Details about some of the famous characters in the series and an in-depth explanation of Quidditch - the fictional sport played by the student wizards in the best-selling books - are promised.
Speaking at a press conference at the Victoria and Albert Museum in Kensington, central London, Rowling said the Pottermore site was a place for fans to "share" the books.
She said: "I wanted to give something back to the fans that have followed Harry so devotedly over the years, and to bring the stories to a new digital generation.
"I hope fans and those new to Harry will have as much fun helping to shape Pottermore as I have.
"Just as I have contributed to the website, everyone else will be able to join in by submitting their own comments, drawings and other content in a safe and friendly environment."
Fans will be able to work their way through the books and follow Harry to Hogwarts. They will be sorted into one of the school's rival houses and become student wizards themselves by casting spells and mixing potions.
Potter fans can register from today for an online challenge that goes live on the website on July 31.
Rowling admitted that working on the project had allowed her to "stay in touch" when she was writing the stories. She said: "It is true to say that finishing writing Harry, I have only cried that much, ever in my life, when my mum died.
"I've never cried for a man like I've cried for Harry Potter."