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Chinese censors must reportedly learn a history previously unknown to them so they know which information the government wants them to stop from spreading.

Employees of censorship companies like the Beijing-based Beyondsoft are taught about the government's violent suppression of the 1989 student-led Tiananmen Square protests and late activist Liu Xiaobo, who was repeatedly imprisoned for his anti-government views, The New York Times reported Wednesday.

This training enables censors to spot content that angers the Chinese government, so they can scrub it on behalf of the country's media companies, which must shut down anything that makes the ruling Communist Party look bad -- even though this is a resource-intensive process.

Many of the online media companies employ thousands of censors, despite exploring the use of artificial intelligence (AI) for the same work, the Times noted. The problem is that politically sensitive content can still easily slip past algorithms.

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Beyondsoft's software looks through web pages and color-codes sensitive words, according to the report. If it reaches a certain threshold, a human worker will review the page.

Even though the information about the reality of China's history is a revelation to employees, one censor said his sense of duty stops him from spreading the information beyond the workplace.

"This information is not for people outside to know," censor Li Chengzhi told the Times. "Once many people know about it, it could generate rumors."

Despite the problem of censorship leading Google to exit China's search engine market in 2010, reports last year suggested that Google looked into introducing a censored search engine -- known as the Dragonfly project -- to the country.

Beyondsoft didn't immediately respond to a request for comment.

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