The document discusses how inbound marketing has become a revolution in customer acquisition due to changes in human behavior and the online landscape. It outlines how people research options extensively online today before making purchases. This represents a shift away from interruptive, outbound marketing tactics towards content-driven inbound strategies. The document provides numerous examples of effective inbound tactics like search engine optimization, social media, blogs, videos and more. It emphasizes that inbound channels now drive the vast majority of web traffic but receive a small fraction of marketing investments compared to outbound paid channels.