Are all criticisms of the government then prohibited? Not exactly. Despite Beijing’s willingness to devote considerable resources to controlling internet content, the government simply cannot ensure that all objectionable content is removed all the time. So they prioritize. Researchers at Harvard found, in a study published earlier this year, that Beijing tolerates some criticism but not calls for collective action. Complain about government corruption? No problem. Attempt to organize a protest on Sina Weibo? No way.
.. In effect, China has two parallel levels of censorship. The first is the relatively free-wheeling atmosphere of sites like Sina Weibo, where the government uses paid advocates — prisoners, for example, can get their sentences reduced by writing pro-Beijing content online — and selective censorship to prevent objectionable content from gathering momentum.