Censorship on Tiananmen Anniversary Cripples Chinese Ne

June 4 isn't just the 20th anniversary of the Tiananmen Square massacre in China, it's also known as Chinese Internet Maintenance day.

Despite that censorship, the country is still very interested in the events of 20 years ago, when the government crushed an unprecedented pro-democracy protest in Beijing by unleashing the army on unarmed students.

"It's hard to talk about censorship because the word for censorship gets censored," MacKinnon said.