Imagine if when you got a book, you also got a mobile app that contained the footnotes and index, supporting material and the searchable text. The app sits inside the book itself. Search the app for “Leonardo da Vinci” and it points you to the relevant pages in the book. Supplementary material is accessed by typing in the page you’re on in the book. It includes biographical information, galleries of high-resolution, zoomable images. Take notes, save and email them. Find other readers nearby. Annotate the text, and keep those annotations in the right place – connected to the book itself, but accessible anywhere. For series books the possibilities are even bigger: linking a collection via a digital index and archive. And its updatable: the author can add in material to the book indefinitely after publication – and pitch their next one when it comes out.