I am an Amazon and Kindle fan. Generally, Amazon ebooks are less expensive than alternatives and very quick to download. I like Amazon Charts. They show the most sold and most read top twenty in fiction and non-fiction now.
J.K.Rowling's first book," Harry Potter and the Philosopher's Stone" was published on June 26, 1997. More than 20 years later, several of the books in the series are on Amazon's charts as very often read and very often purchased. Any way you look at it, she is an amazing phenomenon. If you watch the movie story of her life, "Magic Beyond Words", you may decide she is even more amazing than you thought. Joanne Kathleen took a trip to Spain, met a guy she liked, became a single mom, returned to her native Scotland and got on welfare. She became the world's first billionaire author. She gave away much of her wealth to charities but is still among the most wealthy people in the United Kingdom.
Rowling has other books besides the Harry Potter series. Lynn and I have read aloud the "Robert Galbraith" series, written by Rowling under a pen name.
There is considerable information about Rowling (properly pronounced Roh-ling, rhymes with no-ling) in Wikipedia and her life and adventures. Rowling has her own extensive website, Pottermore, and has original writings there, among other things.
