Nir Eyal and Ryan Hoover have written the definitive book about how to craft a habit-forming product. The book—Hooked: A Guide to Building Habit-Forming Products—has rocketed to success in just its first five weeks of availability, catching the attention and admiration of many thought leaders in their industry. What's fascinating about Nir's and Ryan's work is not only how they developed, (self-) published, and marketed the book to such quick success but also, and more intriguing to me, the parallels between how their 'Hooked Model' for engineering software products (e.g. mobile apps) can help authors create and market irresistible books. Like it or not, books are a specific type of product. And in our digital world, authors of books and related content published on the web can stand to learn a lot from Nir and Ryan, two guys who live and breathe exactly what they teach.