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Unveiling the Secrets of Viral Ideas: A Summary of “Contagious” by Jonah Berger

‘Contagious: How to Build Word of Mouth in the Digital Age’ is a fascinating exploration of viral marketing written by Jonah Berger, an associate professor of marketing at the Wharton School of the University of Pennsylvania. In the book, Berger presents and explains six fundamental principles that drive things to become contagious, i.e., to spread rapidly from person to person.

Berger’s “STEPPS” model is the cornerstone of the book. This acronym stands for Social Currency, Triggers, Emotion, Public, Practical Value, and Stories. The author argues that understanding and leveraging these six key factors can empower individuals and businesses to create content that’s inherently shareable and has the potential to go viral.

Social Currency:

Berger proposes that people care about how they’re perceived by others, so they share things that make them look good in their social circles. For instance, if a product or idea is unique, novel, or exclusive, people are more likely to talk about it because it boosts their social status. Berger cites the example of the secret bar ‘Please Don’t Tell’ in New York, which gained popularity due to its secretive and exclusive nature.


This principle involves the idea that the environment can prompt people to think about related concepts and ideas. If something is top of mind, it’s tip of tongue. For example, mentioning peanut butter often reminds people of jelly, a commonly associated concept.

Emotion: Berger suggests that when we care, we share. Emotionally charged content is more likely to be shared. This principle is demonstrated in the book by Berger’s analysis of New York Times’ most-emailed articles, where he finds a strong relationship between the emotional intensity of an article and its likelihood of being shared.

Public: The things that are more visible are more likely to become viral. If a product or idea is publicly shared or seen, it’s more likely to be discussed. The ‘Movember’ campaign, where men grow mustaches in November to raise awareness for men’s health issues, is a prime example of this principle in action.

Practical Value: Useful information is more likely to be shared because people like to help others. An example in the book is the high sharing rate of articles and posts that contain helpful tips or advice, such as how to save money on energy bills.

Stories: People are more likely to remember information if it’s woven into a narrative. Great stories provide a narrative transportation, which carries the idea or message along. The legendary story of Jared, the man who lost a substantial amount of weight eating Subway sandwiches, is one of the stories cited by Berger.

Through an engaging combination of research studies, anecdotes, and real-world examples, Berger makes his STEPPS framework both accessible and applicable. By understanding and leveraging these principles, marketers and businesses can craft more effective messages, advertisements, and products that leverage word of mouth to reach a wider audience.

‘Contagious: How to Build Word of Mouth in the Digital Age’ offers a fresh and actionable take on viral marketing. Whether you’re a marketer, entrepreneur, or just someone interested in understanding why certain things catch on while others fail, Berger’s book provides a comprehensive roadmap for creating content that’s inherently contagious.