J.K. Rowling's boy wizard first appeared on bookshelves 21 years ago, and in the time since Harry Potter has blossomed into a cultural phenomenon. From films to fan fiction to gifs and memes, Hogwarts is no longer limited to the page, existing across myriad media outlets. In their book, "Transforming Harry: The Adaptation of Harry Potter in the Transmedia Age," Dr. John Alberti and P. Andrew Miller compiled essays exploring the various ways Harry Potter fans engage with the wizarding world, and they joined us in the studio for a lively chat about the boy who lived.