The document discusses key concepts related to how information spreads online such as hyperlinks, page rank which determines search result order, social graphs which map connections between users, and recommendations which can drive adoption through word-of-mouth or viral marketing where users promote products to each other rather than through traditional ads.
4. It is a truism that the greatest internet success stories dont advertise their products. Their adoption is driven by viral marketing that is, recommendations propagating directly from one user to another