From Professor McGonagall's love for a Muggle as a young woman, to how the Dursleys met; from new information about Slytherin, Ravenclaw and Hufflepuff houses, to details about wand wood, the fresh Potter background from the author already stretches to 18,000 words, with more to come.

For the moment, Pottermore will be restricted to the world of the first book, Harry Potter and the Philosopher's Stone, but all the books will be added in due course.

The platform features a host of newly commissioned illustrations and interactive gaming elements. When you register, you get to choose a magic username and then travel through different parts of the book, joining Hogwarts in the virtual world just as Harry does in the books.

In each chapter there are interactive "moments". In the first book there are 44 of these moments. One such example includes Diagon Alley where you can enter Gringots (the wizard bank) and pick up 175 galleons -- the in-game currency. You can then use this to buy items on your shopping list from shops such as Wiseacre's Wizarding Equipment.

On the journey to Hogwarts you can explore a virtual train carriage, finding digital trinkets such as magic beans and a different spell cards that you can add to your personalised trunk for use later. The trunk can be accessed on your profile page which shows all of your friends, digital wallet, all of your digital items, details about the wand you have and the house you are in.

The Sorting Hat -- which allocates users to a Hogwarts house -- is a lot of fun. You go through a series of multiple choice questions to assess your character. Based on your unique responses you get allocated a house -- Gryffindor, Hufflepuff, Ravenclaw or Slytherin. I volunteered to be sorted into a house in the press conference and got sorted into Gryffindor.

Having been sorted into a house, you can challenge fellow students to wizard duels or by successfully mixing potions in order to win points for you house. This part seems to play a little like a multiplayer game -- with leagues of point winners competing against each other.

"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 generation," Rowling revealed. "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. Pottermore has been designed as a place to share the stories with your friends as you journey through the site."

"This is free," added Rowling, who has sold more than 450m copies of the Potter books worldwide. "You don't have to pay to get extra materials, you don't have to buy a single thing. That was really important to me. This was about the 'give-back'."

Although Rowling said it was "impossible to overstate what Harry Potter means to me", Pottermore will be the only way fans will be able to get fresh material from Rowling about Harry's world. "I'm pretty sure I'm done on the novel front," she said.