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10.1 Introduction

Word-of-mouth marketing is powerful. Edelman’s 2010 Trust Barometer shows that 44 percent of respondents trust “a person like me” as a spokesperson.“Edelman Trust Barometer 2010,” Edelman, 2010, (accessed May 10, 2010). In Chapter 8 "Social Media", you learned some of the ways that marketers can tap into the media that promote this kind of trust. Messages passed on from “a person like me” is word-of-mouth marketing, and online that same message can be passed on through social media.

Viral marketing is a form of word-of-mouth marketing that aims to result in a message spreading exponentially. It takes its name from a virus because of the similarities that marketers aim to emulate:

  • It is easily passed on.
  • The number of people who have been “infected” grows exponentially.


The term “viral marketing” was probably first coined by Jeffrey Rayport in an article “The Virus of Marketing” in the December 1996 issue of Fast Company.Jeffrey Rayport, “The Virus of Marketing,” Fast Company, December 31, 1996, (accessed May 10, 2008). That’s not to say that there weren’t viral marketing campaigns before that, but as the Internet developed, so have the electronic tools for passing on information.

Word of mouth has existed as long as there have been words and mouths, but it is a fairly recent phenomenon in the world of marketing. Positive word of mouth can have a tremendous impact on a brand and can take up little to nothing of the marketing department’s budget. However, planning for and measuring word of mouth can be tricky and unpredictable.

As the connected nature of the Internet has allowed for easier spreading and tracking of word-of-mouth information, it has become possible to see how this can be modeled on the spread of a virus in a population.