Hooked: How to Build Habit-Forming Products is a popular book written by Nir Eyal with contributions from Ryan Hoover. The book explains how successful products create habits that keep users engaged.

It introduces the Hook Model, a four-step process—Trigger, Action, Reward, and Investment—that guides product design to encourage repeated use. Using real-world examples from tech companies, it shows how to create products that users return to naturally, without relying on heavy advertising.

The book also emphasizes ethical considerations in building habit-forming products, helping creators balance business goals with user well-being.

Overall, Hooked is a practical guide for entrepreneurs, product designers, and marketers to understand the psychology behind user habits and create engaging, successful products.