Who are dissidents? What role did they play in the Tiananmen protests of 1989?

In 2013, more than 150,000 participants braved the torrential rains in Hong Kong and Macau to remember the 1989 student protest movement, according to organisers; police estimated the turnout to be 54,000.[1] There was a similar vigil in the Taiwanese capital.

In the run-up, the authorities in the People's Republic of China detained and silenced dissidents as in previous years. Families who had hoped to observe the day mourning those who died were intimidated. Policing was stepped up to ensure that no protests took place in or around Tiananmen Square. The Great Firewall was at work blocking sites or removing any references and images that refer to or even hint at the upheavals of 1989. I DONT KNOW IF IT IS CORRECT

Explanation: