Productivity

Hooked: 8 key ideas

by Nir Eyal

The core ideas of Hooked, each in under a minute, written in our own words. Want the full depth? Get the book.

1. IDEA 1 OF 8

   Habit-forming products follow a loop

   Eyal describes the Hook Model, a four-step cycle that many habit-forming products use: trigger, action, variable reward and investment.

   Each pass through the loop makes users more likely to return without being prompted.

2. IDEA 2 OF 8

   Triggers start the habit

   A trigger is what prompts a user to act.

   External triggers include notifications and buttons, while internal triggers are feelings such as boredom or loneliness. Eyal argues that lasting habits form when products become linked with internal triggers.

3. IDEA 3 OF 8

   Make the action easy

   Drawing on BJ Fogg's behaviour model, Eyal explains that an action happens when motivation, ability and a trigger come together.

   Designers increase use by making the desired action as simple as possible, like a single tap or scroll.

4. IDEA 4 OF 8

   Variable rewards keep people curious

   Unpredictable rewards are more compelling than predictable ones.

   Eyal describes three kinds: rewards of the tribe, such as likes; rewards of the hunt, such as new information; and rewards of the self, such as mastery or completion.

5. IDEA 5 OF 8

   Investment brings users back

   In the investment step, users put something into the product, such as data, content or followers.

   This stored value makes the product more useful over time and loads the next trigger, so users are more likely to return.

6. IDEA 6 OF 8

   Habits form in the habit zone

   Eyal argues that products become habits when they are used frequently and are perceived as useful.

   Products in this habit zone can become part of daily routines, while rarely used ones depend on conscious decisions.

7. IDEA 7 OF 8

   Painkillers beat vitamins

   Eyal compares products to vitamins, which are nice to have, and painkillers, which solve an urgent problem.

   Habit-forming products often start as vitamins and become painkillers, relieving a small, recurring itch such as boredom or uncertainty.

8. IDEA 8 OF 8

   Use the Manipulation Matrix

   Eyal offers a Manipulation Matrix to help designers judge ethics.

   It asks whether the maker would use the product themselves and whether it materially improves users' lives, encouraging designers to build habits that genuinely help people.