According to this FAZ article, only 4% of European Internet users are responsible for 80% of all brand-related opinions. These relevant users are called "influencers" and hardly ever produce own content. Instead, they share their opinions and reviews by distributing material they found elsewhere on the web: In blogs or on websites of an estimated another 11% of users called "mass mavens". In a combined effort, mass mavens and influencers might reach an audience of more than one million people. Curiously enough, marketing executives seem to have problems tracking these influencers down, though. Sounds like a rather lame excuse for not being able to convince them of promoting their goods...?