J.K. Rowling, author of the overwhelmingly popular Harry Potter series, discusses her initial inspiration for the book series on her website. She describes her experience on a train in 1990, where the idea for the The Philosopher’s Stone “simply fell into [her] head”.
She described her great excitement over the idea, and her frustration at her lack of a working pen. This lack of an outlet caused her to only sit and think for the next four hours, beginning the creation of Hogwarts and the world of Harry Potter. She adds that the frustrating lacks of a pen may have actually improved her process greatly, as she may have overthought and stifled her growing ideas if she had written them down. Following this line of thinking, Rowling then spent five years planning out every detail of the Wizarding World. Rather than making up the details of her story as she went along, Rowling spent a great deal of time creating an entire world around her stories, which must have contributed greatly to the flow of the completed series.
Rowling’s process puts me a bit in mind of J.R.R.Tolkien, who created the entire world of Middle Earth, complete with entire languages, to create The Lord of the Rings, along with his other novels.
A look through Rowling’s website provides a lot of interesting insight into her works as an author. Take a look at her site here