Fifty years ago, few people could have guessed some of today's most common habits. Habits like having a mobile phone within arm's reach at all times; checking Facebook or email multiple times an hour, or calling an Uber instead of a cab. All companies dream of inspiring such new and compelling habits in their customers, but few manage to achieve it. Nir Eyal, author of Hooked: How to Build Habit-Forming Products, shares his theories on what sets these products apart.