A: I tend to think of Viral Marketing that include both systematic and unsystematic ways that your current customers acquire new customers, including:
- Chain letters
- Tupperware parties
- Youtube embedding
- E-mail forwards
- Consumer “buzz”
- … etc
In some of these cases, the virality has been “built-in” to the system – for example, but chain letters explicitly promise you something in return for sending on a letter, as do Multi-Level Marketing systems like Tupperware. These incentives and systematic design are originated with the intent to propagate a viral process.
On the other hand, when I think of Word of Mouth, however, I specifically think of consumers telling other consumers about a product just because they like it, rather than there being a direct incentive to do so. This feels more organic or natural to me, and perhaps, it’s what people usually think of as your passionate influencers propelling your company forward.
Perhaps this distinction is arbitrary, but it helps serve the point that viral marketing can be defined very broadly – beyond word of mouth and other “natural” vectors.