James Fallows on how China censors the internet:

Taken together, the components of the control system share several traits. They’re constantly evolving and changing in their emphasis, as new surveillance techniques become practical and as words go on and off the sensitive list. They leave the Chinese Internet public unsure about where the off-limits line will be drawn on any given day. Andrew Lih points out that other countries that also censor Internet content—Singapore, for instance, or the United Arab Emirates—provide explanations whenever they do so. Someone who clicks on a pornographic or “anti-Islamic” site in the U.A.E. gets the following message, in Arabic and English: “We apologize the site you are attempting to visit has been blocked due to its content being inconsistent with the religious, cultural, political, and moral values of the United Arab Emirates.” In China, the connection just times out. Is it your computer’s problem? The firewall? Or maybe your local Internet provider, which has decided to do some filtering on its own? You don’t know. “The unpredictability of the firewall actually makes it more effective,” another Chinese software engineer told me. “It becomes much harder to know what the system is looking for, and you always have to be on guard.”...

Chinese bloggers have learned that if they want to be read in China, they must operate within China, on the same side of the firewall as their potential audience. Sure, they could put up exactly the same information outside the Chinese mainland. But according to Rebecca Mac­Kinnon, a former Beijing correspondent for CNN now at the Journalism and Media Studies Center of the University of Hong Kong, their readers won’t make the effort to cross the [Great Firewall] and find them. “If you want to have traction in China, you have to be in China,” she told me. And being inside China means operating under the sweeping rules that govern all forms of media here: guidance from the authorities; the threat of financial ruin or time in jail; the unavoidable self-censorship as the cost of defiance sinks in.