The Great Firewall in China

The Great Firewall is the name that has come to be used for this sprawling censorship and surveillance system in China. It kind of controls everything from blocking Facebook and Twitter, but also to the type of censorship that happens on the Chinese internet itself. At the beginning it was just a blacklist of sites that had to be blocked by ISPs, porn, very obviously controversial political sites, things like that. But it's really evolved over time to have hordes of human sensors who are checking posts and deleting and restricting topics and certain things.