Knowledge-sharing and influence in online social networks via viral marketing

Online social networks are increasingly being recognized as an important source of information influencing the adoption and use of products and services. Viral mar-keting—the tactic of creating a process where interested people can market to each other—is therefore emerging as an important means to spread-the-word and stimu-late the trial, adoption, and use of products and services. Consider the case of Hotmail, one of the earliest firms to tap the potential of viral marketing. Based predominantly on publicity from word-of-mouse 4, the Web-based email service provider garnered one million registered subscribers in its first six months, hit two million subscribers two months later, and passed the eleven million mark in eighteen months 7. Wired magazine put this growth in perspective in its December 1998 issue: “The Hotmail user base grew faster than that of any media company in history—faster than CNN, faster than AOL, even faster than Seinfeld’s audience. By mid-2000, Hotmail had over 66 million users with 270,000 new accounts being established each day.” While the potential of viral marketing to efficiently reach out to a broad set of