New Harry Potter content has been written by JK Rowling and it is available on Sony's Pottermore website.
The first chapters of Harry Potter and the Prisoner of Azkaban have been unlocked and offer fans explanations they have long been waiting for.
Pottermore is a free-to-use online reading experience based around the Harry Potter books. In order to get the new content, users must read through Harry Potter and the Chamber of Secrets.
They must also collect all the items for the second-year shopping list, which are in chapter 4 of the Chamber of Secrets.
Secrets revealed in the new chapters include the reason why Harry's Aunt Marge is so mean, why people should never take a hot drink on the Knight Bus and the story behind the Hogwarts portrait of Sir Cadogan and his little fat pony.
According to hypable.com, "Marge is a large and unpleasant woman whose main interest in life is breeding bulldogs. She believes in corporal punishment and plain speaking, which is what she calls being offensive.
"Marge is secretly in love with a neighbour called Colonel Fubster, who looks after her dogs when she is away. He will never marry her, due to her truly horrible personality. This unrequited passion fuels a lot of her nasty behaviour to other people."
Sir Cadogan; Knight of the Round Table
Explaining Sir Cadogan's portrait, the new content says: "It is widely believed in wizarding circles that Sir Cadogan was one of the famous Knights of the Round Table, albeit a little-known one, and that he achieved this position through his friendship with Merlin.
"He has certainly been excised from all Muggle volumes of King Arthur's story, but wizarding versions of the tales include Sir Cadogan alongside Sir Lancelot, Sir Bedivere and Sir Percivale. These tales reveal him to be hot-headed and peppery, and brave to the point of foolhardiness, but a good man in a corner."
The Knight Bus and hot drink quandary is explained as: "The Knight Bus was so-named because, firstly, knight is a homonym of night, and there are night buses running all over Britain after normal transport stops. Secondly, 'knight' has the connotation of coming to the rescue, of protection, and this seemed appropriate for a vehicle that is often the conveyance of last resort.
"The driver and conductor of the Knight Bus in 'Harry Potter and the Prisoner of Azkaban' are named after my two grandfathers, Ernest and Stanley."
It also reveals why Rowling regrets making Aunt Marge a breeder of bulldogs.
Last week, Pottermore asked its users to pick the moment they would like revealed in the sneak-peak of the forthcoming chapters.
They picked Hagrid's First Lesson. It reads: "In this Moment, Harry, Hermione, Ron and their classmates attend Hagrid's first Care of Magical Creatures class and encounter the impressive Hippogriffs in their paddock."