Following the Hotmail link revolution, Juvertson and Draper were the first ones to define viral marketing as "a network enhanced word of mouth" phenomenon (1997). Sixteen years later, more precised definitions have been formulated. According to Dictionary.com, Viral Advertising represents "a marketing strategy that focuses on spreading information and opinions about a product or service from person to person, especially by using unconventional means such as the Internet or e-mail" (2013).
Looking at the history, the first notion of Viral Advertising was created in 1996 by Hotmail.com with the implementation of a 'Join Now for Free' link to their page on every single email sent by existing Hotmail users. The viral tool allowed Hotmail to promptly increase its customer database as the number of users expanded from few hundreds to 12 million in 1998. (Internet Marketing Dictionary, 2013) (Grainger, 2009)
Focusing on its component, the most important element of viral advertising is the key role played by the target audience which ensures the spreading and 'buzz effect' allowing the advertisement to be seen by a larger public. (Definitions Marketing, 2013)
However the target audience will only share the advertisement content assuming the presence of certain kinds of values such as comedy or emotions. (Pickton and Broderick, 2005)
Indeed in the case of a successful viral advertising campaign, the core of the advertisement's exposition is due to social word-of-mouth and not traditional advertising space purchases. Therefore all efforts in the viral advertising campaign creation are concentrated in the creative and innovative aspects.
Viral marketing provides many advantages, some of the most important ones are its "cost-effectiveness, exponential reponse rate with time" and the fact that the message conveyed will not be perceived as a spam because it was send by a known individual, which has more impact as customers shift their reliance and trust from formal marketing representatives to comrade users. (Internet Marketing Dictionary, 2013) (Acker et al, 2011)
Viral advertising evolved from an email-based campaign targeting few million of users to varied social networking platforms reaching billion of people (AdAge, 2013).