Hooked... how to build habit-forming products... by Nir Eyal, an entrepreneur on a mission to discover what makes certain startups an integral part of pop culture. -- Sign up to receive a new book summary every week: www.bookvideoclub.com --

Years of studying successful startups led to insights about influencing consumer behavior. And then, these insights were codified in the Hook model: a cycle of events, engineered to keep users coming back.

The Hook cycle consists of 4 stages: trigger, action, variable reward, and investment.