Tiananmen Square: 20 years later
A member of China's People's Liberation Army (PLA) stands guard in Tiananmen Square in Beijing. Authorities blocked social networking and image-sharing Web sites such as Twitter and Flickr and confined dissidents to their homes or forced them to leave Beijing, as they ramped up efforts to prevent online discussions about or commemorations of those who died in the military assault on demonstrators on the night of June 3-4 1989. Nelson Ching/Bloomberg News
