China is getting better at filtering
China used to block whole sites. Now its censoring technique is more refined, filtering web pages based on blacklisted keywords in the pages' URLs, or in the pages themselves.
Internet providers/companies are self-censoring
Internet filtering occurs at many levels, from the central nodes of China's networks, to Internet service providers (ISPs) to local cyber cafes. Private Internet companies that run search engines, chat rooms and web logs, including U.S. giants Yahoo, Google and Microsoft, are required to censor themselves, and to provide information about their users to Chinese authorities.
China's filtering varies from place to place and over time
There's evidence that China employs stricter filtering during politically sensitive times, such as the March 2006 Communist Party Congress and around the anniversary of the Tiananmen Square uprising. And filtering can vary based on what ISP is operating in a given region; a user in Shanghai might be able to view pages a user in Beijing cannot. Americans traveling in China report that filtering seems less stringent in western hotels and housing districts that are primarily for foreigners in comparison to the more heavily policed Internet cafes.
It's not just computers
After citizens used cell phone text messages to circumvent the news blackout about the 2003 SARS outbreak, the Communist Party regime announced it would filter text messages. But it's unclear just how vigorously China has pursued this.
Software to circumvent filtering exists, but few Chinese use it.
Several Western software developers have written programs to help users access blacklisted content. But just a very small number of Chinese use them. Some China observers think the Western media focus too much on the censorship issue in China.