"We're now entering a new period in the history of publishing," said author George RR Martin. "The digital book gives readers the ability to experience all this rich secondary material that had not been possible before. These enhanced editions available only on iBooks include sigils and family trees and glossaries. Anything that confuses you, anything you want to know more about, it's right there at your fingertips. It's an amazing next step in the world of books," he says.

All of the five books, however, will not release at the same time. For now, only the first book, A Song of Ice and Fire is available for download. The digital edition of the second novel, A Clash of Kings, is scheduled to release on 27 October, while the third book, A Storm of Swords, is due on 15 December. There are no specific dates for the release of the fourth and fifth books, A Feast for Crows and A Dance of Dragons respectively but they will release sometime in February and March 2017.

Apart from the five books which have already been well-received by book lovers and turned into one of the most iconic television dramas by HBO, fans are particularly looking forward to Martin's next book, The Winds of Winter.

Publishers HarperCollins have remained mum about a publication date for The Winds of Winter saying: "As yet nothing has been finalised regarding the publication ... but when the book is ready, it will be announced through George's website."

Martin has expressed his desire to write another book post Winds of Winter after which he says the series of books will come to a close. The 68-year-old author is said to have already revealed the ending of the books to the HBO series creators David Benioff and DB Weiss in case he is unable to finish the novels.