Researchers from OpenNet Initiative (ONI) released an excellent report last year on the scope and degree to which China filters Internet content. Though quite a few countries filter Internet content, the researchers agree that "China's Internet filtering regime is the most sophisticated effort of its kind in the world." They describe it as "pervasive, sophisticated and effective" and it is supported by a number of laws and regulations that tend to make Internet Service Providers, Internet Business Owners and Internet Content Providers agents charged with carrying out the government monitoring and censoring plans.

Though there is no way to be completely certain of China's exact process for reviewing sites, tests conducted by ONI confirm that filtering takes place on a multitude of levels. While a great deal of content can be (and is) blocked by a list of search terms (some of which can be easily guessed, but most of which are not public knowledge), it was confirmed through the study that the filtering system is actually dynamic in nature, which has made it difficult to conclusively describe the system.

Content containing the following topics (with any related terms) is largely inaccessible online in China:

• pro-democracy/pro-Western commentary 
• Falun Gong
• Tibetan independence
• Taiwanese independence
• Opposition political parties
• anti-Communist movements/statements
• Criticism of China's human rights and social justice records
• Independent news media

The government delegates the content monitoring role to Internet Service Providers (ISPs), search engines and even blog service providers and instant messaging software programs by requiring them to search and filter content. ISPs are held legally responsible for any content that is able to be displayed through their service. They are required to track usage statistics (including sites visited) and keep this information on record for 60 days. Should a customer violate a cyberlaw (such as eschewing filters), the ISP will also be held responsible. 

With regard to the actual mechanics to filtering, testing pointed to the existence of several points of filtering. Note that the ones with asterisks next to them show that while this method is in use, it appears to be used inconsistently, suggesting that some content is more sensitive than other content.

• China's gateway filtering (filtering keyword searches at the backbone level) 
• IP Address Blocking*
• Domain-level filtering
• URL filtering (Sites blocked but top level domains available)
• E-mail filtering* (filtered by individual email service providers)
• Blog filtering* (blocked or edited for content by individual blog service providers)
• Google cache filtering* (some keywords are blocked even when attempting to bypass filtering system by altering the HTTP GET request)
• Chinese search engines (filters results)
• University Online Bulletin Board Systems (monitored by universities)
• Online Discussion Boards* (monitored by webmasters; level of filtering varies by forum; those who post unacceptable material are 'blacklisted' by being blocked from using User ID, or, in some cases, arrested)

The researchers conclude that "China's advanced filtering regime presents a model for other countries with similar interests in censorship to follow. It has also shown a willingness to defend and even promote the principles of its filtering regime to international venues governing global communications….While there can be legitimate debate about whether democratization and liberalization are taking place in China's economy and government, there is no doubt that neither is taking place in China's internet environment today."