Astroturfing is building opinions by faking or artificially mis-weighting some opinions, like using fake accounts on social networks to vote and contribute with

Astroturfing is building opinions by faking or artificially mis-weighting some opinions, like using fake accounts on social networks to vote and contribute with a particular sentiment, making it look like more people feel that way than actually do. What Facebook does is to allow and disallow certain types of content based on public guidelines. Even if those rules are nonsense, unfair or politically motivated, it's at least not done secretly unlike real astroturfing.