Viral marketing is an idea that spreads--and an idea that while it is spreading actually helps market your business or cause.
A second kind has evolved over the last few years, and that's a marketing campaign that spreads but isn't the product itself. Shepard Fairey's poster of Barack Obama was everywhere, because people chose to spread it. It was viral (it spread) and it was marketing (because it made an argument--a visual one--for a candidate.)
Something being viral is not, in an of itself, viral marketing. Who cares that 32,000,000 people saw your stupid video? It didn't market you or your business in a tangible, useful way.
Marketers are obsessed with free media, and, as is often the case, we blow it in our rush to get our share. We create content that is hampered or selfish or boring. Or we create something completely viral that doesn't do any marketing at all.
Source by: Viral Marketing.....