It's been 25 years since the end of the uprisings in Tiananmen Square.
Tanks rolled into the square and soldiers sprayed bullets into the crowds, killing hundreds of protestors and injuring thousands more. The massacre led to many more more being rounded up and imprisoned.
Today the numbers 6/4 are censored by the Chinese government. As are any references to the Tiananmen Square, such as the innocent 'today' or 'tomorrow'. Even numerical passages like 63+1, 65-1 are censored by the Chinese government.
Despite the best efforts of some dissidents whole generations in China have grown up by and large ignorant of the protests (and the subsequent slaughter of many protestors) at Tiananmen Square.
In the past, small discussions have been allowed in private homes to commemorate the event but this year is different, even those discussions have been banned. This year alone at least fifty people have been targeted by the Chinese authorities detention and harassment. Including the 77 year mother of a protestor who was killed in the protest Ding Zilin, who is an outspoken critic of the Tiananmen Square massacre, has been singled out for harassment.