We expect an ad to sell us on how great the product is, but out friends have got our back. They will tell us what they honestly think about a product as they have no ulterior motive.
Companies create traditional advertisements for a wide audience.
An ad on the evening news, for example, will be put in front of the millions watching (though only a portion of the viewers will actually see it.)
Word of mouth, on the other hand, is more targeted; being spread organically on a smaller scale, to people who are already interested.
The 6 Principles That Make Things Contagious
According to Berger, any product, idea, or behavior can be contagious – as long as you build in the following principles.
#1 Social Currency
There are three ways to leverage social currency:
Find inner remarkability. Share entertaining, innovative, or gripping stories that make your product, service, or information more interesting for people to talk about.
Leverage game mechanics. People enjoy competition and they especially enjoy sharing status symbols like awards and prizes. Adding the element of "gamification" or something similar gives people an incentive to show off your product to others.