British writer J.K. Rowling, author of the Harry Potter series of books. (Suzanne Plunkett/Reuters)

“Although I’ve enjoyed writing it every bit as much, my next book will be very different to the Harry Potter series, which has been published so brilliantly by Bloomsbury and my other publishers around the world,” Rowling said in a statement. “The freedom to explore new territory is a gift that Harry’s success has brought me, and with that new territory it seemed a logical progression to have a new publisher. I am delighted to have a second publishing home in Little, Brown, and a publishing team that will be a great partner in this new phase of my writing life.”

The “Harry Potter” books became the fastest-selling in history, and the series has been translated into more than 70 languages. Rowling has expanded the brand into an amusement park and Web site, Pottermore. Fans who have followed Rowling since the first book, which was released in 1998, are college-age and older, and they’re ready for something a little more-grown-up, while remaining doggedly loyal to the author. Reactions on Twitter have been overwhelmingly positive. Here are a few:

Sometimes I wonder what we ,as potterheads and human beings,did to deserve such a wonderful soul lead/guide us in life.Thank you JK Rowling.

— Donna Tyler. (@FREDFINNIGAN) February 23, 2012

JK Rowling announcing a new book is almost like god announcing a follow-up to the Bible.

— Natalie Summers (@Nat_Summers) February 23, 2012

Yes, it’s true. Much like her hero Voldemort, JK Rowling will return after years. Greater & more powerful than ever before. #RowlingReturns

— The Dark Lord (@Lord_Voldemort7) February 23, 2012