It's no secret that Western Internet companies have to hew to the party line if they want to do business in China. Google, Yahoo!, and scores of other outfits, both domestic and foreign, have made concessions to China's censors. The latest high-profile example: In December, Microsoft's MSN shut down a Chinese blogger's site at the government's request.

Microsoft maintains it had no choice. "We only remove content if the order comes from the appropriate regulatory authority," says Brooke Richardson, group product manager for MSN.

Getting a phone call from the government is one part of the picture. What few Westerners know is the size and scope of China's censorship machine and the process by which multinationals, however reluctantly, censor themselves. Few also know that China's censors have kept up with changing technologies, from cell phone text messaging to blogs.

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