"Friends and other non-professional influencers"

At its core, the social revolution allows people to consume what they want, when they want, and largely on the recommendation of friends and other non-professional influencers.  Attempt to graft old models onto it and you are doomed to struggle; find models that are native to the medium and you will thrive.
— From¬†It’s Not About You: The Truth About Social Media Marketing by Tim O'Reilly, October 2, 2012.