

A cellphone camera in use at an antigovernment protest in Sanaa, Yemen. Ahmed Jadallah/Reuters
Police in Shanghai, China, try to stop media coverage of an Arab Spring-inspired ‘Jasmine Revolution’ pro-democracy protest organized via social networks. Reuters
An antigovernment protester in Taiz, Yemen, uses a mobile phone to photograph a rally for the ouster of President Ali Abdullah Saleh. Khaled Abdullah/Reuters
Just released from detention, Egyptian Wael Ghonim (with microphone), the Google marketing manager who was a key organizer of the online campaign that sparked the first protest on Jan. 25, talked to the crowd in Tahrir Square, in Cairo in February. Tara Todras-Whitehill/AP
A Thai Buddhist monk checked messages on his cellphone during ceremonies last month to remember those killed in 2010 pro-democracy riots. David Longstreath/AP
Green-clad supporters attended a rally for former Prime Minister Mir Hossein Mousavi, who was a candidate for the 2009 Iranian presidential elections. In the wake of the contested election, the government cracked down on everything from cellphone service to Facebook, and Twitter emerged as the most powerful way to disseminate photos, organize protests, and describe street scenes. Damir Sagolj/Reuters
Iranian technicians monitored data flow in the control room of an Internet service provider in February. Caren Firouz/Reuters
A woman browses the Internet at a cybercafe in Putrajaya, Malaysia, where activists protesting digital censorship hacked into government websites. Bazuki Muhammad/Reuters
An Argentinian woman banged a pan at a 2002 protest of a currency devaluation by the government. The peso crisis protests of the era were some of the earliest examples of digital activism: Protests were organized invisibly in online communication – in the chat rooms and on the e-mail lists of early social media. Andy Nelson/The Christian Science Monitor/File