Nir Eyal, the author and entrepreneur behind the book Hooked: How to Build Habit-Forming Products, talks about the secrets behind the success of companies like Facebook and Twitter. What is it that makes a product habit-forming and even addictive? Nir argues that it's a hook that consists of a chain of events: a trigger, an action, a reward and an investment. In this talk he breaks down the four elements and explains how to use this knowledge of how habits are formed to create great products.