According to Wikipedia the term ‘Viral marketing’ means using “marketing techniques that use pre-existing social networks to produce increases in brand awareness, through self-replicating viral processes, analogous to the spread of pathological and computer viruses.
It can often be word-of-mouth delivered and enhanced online; it can harness the network effect of the Internet and can be very useful in reaching a large number of people rapidly”.
On the first recorded viral campaigns that was used to create awareness of a website were developed by the artist Tim Nolan in 1996. He used abstract pairings of phrases, quotations, lyrics and images to create interest around web based installations. Viral marketing sometimes refers to Internet-based stealth marketing campaigns, including the use of blogs, seemingly amateur web sites, and other forms of astroturfing, designed to create word of mouth for a new product or service. Often the goal of viral marketing campaigns is to generate media coverage via “offbeat” stories worth many times more than the campaigning company’s advertising budget.
On the other hand, the term “viral advertising” refers to the idea that people will pass on and share interesting and entertaining content; usually to promote a particular brand. They will often take the form of a video clips, or interactive Flash games, online games, or images. It is popular because it is relatively cheap to implement compared to other forms of direct marketing and advertising. Most is sent via email and users are directed to a website or phone number with the consequent lack of printing and posting charges.