It has brought hundreds of millions of people online and has become a vast marketplace for digital commerce, yet it is also heavily policed by censors to snuff out any challenge to the ruling Communist Party.
Under President Xi Jinping, the censors are working overtime to keep 721 million Internet users under control.
The latest effort came Monday.
China's national parliament approved a cybersecurity law that can be used to restrict free speech and force foreign Internet companies to heed the demands of China's security services.
Censorship is not new in China; a huge phalanx of officials are devoted to it, harsh punishments are meted out, and the country is ringed by a content-blocking Great Firewall.
But now censorship will be more fully enshrined in the legal code.
Article 12 of the new law prohibits use of the Internet for "inciting subversion of the national regime" or "the overthrow of the Socialist system."
Also banned is inciting separatism or ethnic hatred, "endangering national unity," or "fabricating" or disseminating false information about the economy.
These are all touchstones of Chinese authoritarianism, vague enough to be deployed in many circumstances to smother dissent.
Article 37 of the new law requires "critical information infrastructure operators" to store users' data,including that of foreign companies, on Chinese territory, making it easier for the security services to snoop.
Article 24 requires Internet providers to demand the real identity of those they provide services to - making it easier for security services to track down those who would like to speak their mind.
Many foreign businesses are also alarmed that the new law may give the Chinese authorities access to their technology and data.
Offering a glimpse of how censorship actually works in China, Ronald Deibert, director of the Citizen Lab at the University of Toronto's Munk School of Global Affairs, released a report recently on digital streaming services.
Similar to Periscope (which is banned in China), these apps, such as YY, 9158 and Sina Show, have become a craze.
Deibert's researchers downloaded these three, and between February 2015 and October 2016 extracted 19,464 keywords that trigger censorship on chats associated with each application.
Rather than monolithic control, they found censorship is decentralized and somewhat chaotic; the platforms are often expected to adhere to a kind of "self-discipline" rather than direct orders.
Deibert's group discovered that the most popular app, YY, with 844 million registered users, automatically sends a report back when a user types a banned keyword; the report includes not only the user's name but also who the message was sent to and the message itself.
In law and in practice, China is creating the world's largest online thought prison.
It turns the idea of the Internet as a force for freedom on its head, and as China goes, so go other tyrants.
From Vietnam to Saudi Arabia, from Russia to Turkey, the age of Internet repression has blossomed.
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