As the 25th anniversary of the Tiananmen Square Massacre  approaches the Chinese government's web censors are in full swing to silence online discussions and commemoration of one of the bloodiest events in Beijing's modern history.
The crackdown that initiated on June 3–4, 1989 is also remembered as the “June 4th event”. On this day, armed Chinese troops and tanks attacked unarmed civilians who were trying to block their advance towards Tiananmen Square  in Beijing, where student-led popular demonstrations  had been taking place since spring. The protests were triggered by the death of a liberal reformer, the former Communist Party General Secretary  Hu Yaobang , who was deposed after losing a power struggle with hardliners in the Communist Party over liberal reform.
Estimates of the death toll from June 4, 1989 range from a few hundred to the thousands. The Chinese government has prohibited all forms of discussion or remembrance of the events since.
As anticipated, the most frequently used and censored term on China's web is “June 4″ (六四), the day the massacre took place. A number of other terms, like “Hu Yaobang”, “narrow”, “rejected” and “Mirror Magazine”, all of which are associated with the memoir of Deng Liqun on Hu Yuibang have also been deleted. Keywords related to Hong Kong's politics are also being blocked.
Here are some of the major censored terms featured in the Weibo censored terms word cloud created by Hong Kong University's Weiboscope project, with some examples of the deleted posts that have been saved and made public by Free Weibo .
June 4 (六四: Most censored posts containing “June 4″ sought to honor the 25th anniversary of the event. Some focused on the historical event that happened in 1989. The Chinese government recently arrested  several intellectuals who attended a seminar on the Tiananmen Massacre. News and comments about the arrest were also deleted:
“Hong Kong anti-corruption monster”: This will definitely be deleted. But still I will post a June 4 tweet and get myself banned from Weibo! Heaven will forbid such lies and I will go to hell with the liars.
To Jia: What is the reason for Kong Qindong being blocked? June 4 or Hu Yaobang? There are different versions.
“Can't turn around”: Read that Ye Fu was arrested at midnight, can't sleep. As a writer, he has written the story of heartbroken mothers, pure love and a grassroots society seeking justice… He was arrested for holding a seminar at home about June 4. Damnit. The devils rule the world, good people can't survive.
Tiananmen （天安門: The term Tiananmen was also censored. This year, however, overseas Chinese activists launched a “return to Tiananmen” movement and encouraged individuals to either take photos with a political message at the square or to visit the square on June 4. All posts that talk about the political significance of Tiananmen were removed. Below are two examples:
Jiangnan leisure 2008: If the anti-rightist movement worked, the May 4 Tiananmen movement during the Cultural Revolution wouldn't have happened and the ruling party would not have had a legitimacy crisis upon Mao's death.
Feiming Weibo: Beijing, Tiananmen Square are Mao's residence. Have to take a round turn in June.
Hu Yaobang (胡耀邦）, Old Residence（故居), Firmly rejected (峻拒), the Mirror Monthly（鏡報月刊）and Hu Jintao (胡錦濤: All these terms were deleted because of their relation to a memoir written by Deng Liqun on Hu Yaobang.
The man whose death triggered the 1989 Tiananmen Protests
Hu Yaobang was loved by the political liberals in China. Throughout the 1980s, Hu pursued a series of economic and political reforms under the direction of Deng Xiaoping, the engineer of China's open door policy. A series of student protests that took place in 1987, demanding more political liberation, resulted in an internal party struggle. Hu was condemned for his “bourgeois liberalization” policy and was forced to resign as the party's general secretary. He passed away on April 15, 1989 and indirectly triggered the Tiananmen student protest.
The memoir of Deng Liqun revealed that in 1988, after Hu Yaobang was forced to resign. Deng encouraged him to stand up against his successor Zhao Ziyang, but was rejected. The episode reconfirmed Hu Yaobang's integrity as the country's leader. The fact that the former Chinese President Hu Jintao visited Hu Yaobang's old residence to show respect for the late leader has been interpreted by some  as a political gesture amid the fierce internal party struggle under the leadership of Xi Jinping.
Grassroots Du Nan: What is the meaning of this sign? “Hu Yaobang” is no longer a sensitive term. The screen is full of posts for memorizing Hu Yaobang. No blockage or screening. Hu Jintao visited Hu Yaobang's old residence…
Misty Lanzhou: RT @Nurse from Lao Zhang hospital: [A person's virtue] November 1988, Deng Liqun requested to meet Hu Yuibang in Changsha. He wanted to join hand with Yuibang to overthrow the then CCP chief secretary but was rejected firmly.
Zheng Keqiang […] Secretary of the security guard Li Hanping heard Deng (liqun)'s idea, straightforwardly said: “that's great! Let's retaliate!” Hu Yuibang criticized him: “after so many years you have followed me, I can't imagine you are so narrow-minded!” (Mirror magazine)
Censors zoom in on Hong Kong's Politics
Hong Kong（香港and Leung Kwok-Hung or Long Hair (梁國雄): All these terms relate to Hong Kong politics, and are under heavy censorship as the citizen's civil disobedient campaign, Occupy Central, approaches. Many names from the pan-democratic clans, such as Leugn Kwok-Hung, who is a Legislative Council member and a radical democrat, have become sensitive terms. Apart from specific censorship of people and political events, many political discussions have also been filtered into oblivion. This suggests that the Chinese Communist Party is very cautious about the role of Hong Kong as a diasporic dissent space. Here are some examples of the censored posts related to Hong Kong:
SCMP: #opinion# [ Hong Kong has to defend freedom of speech] The newspaper kiosks in Hong Kong have all kinds of magazines about politics and political leaders, many people ask how come freedom of press is still a concern?
“Time's Myth”: [Difference is household registration] Giving birth in Hong Kong, the baby will obtain Hong Kong citizenship; Giving birth in the USA, the baby will obtain US citizenship […] Giving birth in China, the baby is not necessarily Chinese citizen, it may become illegal because the legal status of life originates from the government's “birth permission”.
Gold at the seaside: Hong Kong Legislative Council members made their official visit to Shanghai. There were only three pan-democrats, who were considering whether or not to proceed with the tour. A pan-democratic council member who carried with him a June 4 T-shirt was repatriated back to Hong Kong. Leung Kwok-hung questioned the sincerity of the trip. Two members from the Labour Party returned back to Hong Kong. Long Hair failed to enter [China], his fans were disappointed.
China sees the Internet as an ideological battlefield. The range of the censored terms in the Weiboscope's word star – names related to the Tiananmen event, the party's historical internal struggle, and Hong Kong contemporary politics – shows just how sensitive the Chinese Communist Party still is about the 1989 Tiananmen Square Massacre, and the extent it is willing to go to make sure that no one talks about it.