politics, especially less on their political stand and views than people in those so-called autocracy countries like Russia and China. People in the west are more cautious in talking about politics in person-to-person situation, primarily fear offending or ruining relationship with neighbors, co-workers and friends. Social media provides a channel for them to express their otherwise hidden political views.
If you listen to talkshows in China you would be shocked to hear so many talks which are deemed political incorrect in the west and so many things that westerners don't talk about in public.