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.
The term "viral advertising" refers to the idea that people will pass on and share interesting and entertaining content; this is often sponsored by a brand, which is looking to build awareness of a product or service.
These viral commercials often take the form of funny video clips, or interactive Flash games, an advergame, images, and even text.
"The Federal Trade Commission has stated that it is going to investigate the use of 'Viral Marketing' by corporations.
This is the type of advertising that seeks to start a word of mouth campaign for the product via consumers themselves. Previously, consumers themselves set the buzz. But lately advertisement firms are stepping up to the plate themselves, seeding the market with buzz that looks independent of the company, but is in fact funded by them.
The crew at Penny Arcade contend that corporate generated buzz is not Viral Marketing, and perhaps Guerrilla Marketing would be a more apt term. Either way, it appears to be a profitable advertising model."