China has what’s probably the world’s most complex and robust internet censorship system, that rests on two main pillars: preventing Chinese citizens’ access to foreign websites and services that have been banned by Beijing, and controlling what kind of information is allowed to appear on the massive domestic social media and messaging scene.
When it comes to the latter, services like Weibo and WeChat are monitored and if need be censored through a filtering system that looks for and identifies “sensitive” words and phrases that are outlawed.