We all know what a book is. It’s made of paper; you hold it in your hands; it contains words and sometimes pictures. We know that books have certain affordances such as ruggedness, ease of reading, portability, and are relatively expensive (at least compared with electronic forms). But perhaps most important, books afford deep attention. They engage and focus. They are relatively unchanging, and so they become cultural references. And these same characteristics also encourage writers and publishers to invest a lot in their creation-knowing that they may well not have a second chance.