Watching How China Censors

As China's 500 million Internet users rapidly adopt social media, academics and entrepreneurs are figuring out ways to track online messages and blog posts to better understand what the government censors—and even how to predict its intent.

China's government employs software and an army of thousands to police the Internet, but it leaves much of the censoring to social-media sites like Sina Corp. to take down posts that violate local and national rules issued each week. While it is generally known that certain words or phrases, such as the Tiananmen Square massacre, will trip the censors, the scope isn't fully understood. These sites usually offer clues that they deleted a post due to censorship—rather than by the user or due to a technical problem—leaving special messages or images such as an Internet police cartoon character. That is helping researchers figure out how China's opaque power structures work to control its citizens. "We have a degree of translucence now about censorship we never had," said David Bandurski, a researcher at Hong Kong University's China Media Project.