Jonah Berger's Contagious: Why Things Catch On explores the science behind why certain products, ideas, and behaviors become popular. 

The book introduces the STEPPS framework—Social Currency, Triggers, Emotion, Public, Practical Value, and Stories—as the six key principles that drive contagiousness. 

Berger uses examples like the "Will It Blend?" videos and the Livestrong wristbands to illustrate how these principles can be applied in marketing and other fields. 

He emphasizes that word-of-mouth marketing, both online and offline, is a powerful driver of consumer behavior, more so than traditional advertising. 

The study examines how factors like social influence, triggers, and emotional arousal can significantly impact whether something gains widespread attention and adoption. 

Ultimately, Contagious aims to provide readers with actionable strategies for creating content and campaigns that are more likely to spread.