At the heart of the book is an examination of the "hook model," a framework that systematically guides designers in creating products that establish and reinforce user habits. It begins with the Trigger phase, exploring how external and internal triggers prompt user action, sparking engagement. Whether through external cues or internal motivations, understanding triggers is fundamental to the creation of products that consistently capture user attention.

Moving on to the Action phase, the book explores the steps users take to interact with the product, emphasizing the role of simplicity and user-friendly design. By dissecting the elements that drive user behavior, the book provides actionable insights for designers aiming to create seamless and intuitive interactions that encourage repeated use.

Crucial to the hook model is the Variable Reward phase, where the book explores the psychology behind unpredictability and its impact on user satisfaction. By incorporating variable rewards into product design, designers can elicit a sense of anticipation and pleasure, further reinforcing the habit loop.