In fact, the social-networking site became so important to the unfolding protests that U.S. officials asked Twitter to delay scheduled maintenance of its global network that would have temporarily cut off service. (Iran is important to the U.S., largely because of fears about its suspected nuclear-weapons program.)
New technologies have always played a role in political movements, especially ones challenging repressive governments. It's even truer today, as the Web and cellphones have expanded their reach to most corners of the world, offering people myriad ways to evade government control. That poses problems for authoritarian governments trying to maintain their grip on informationand their citizensin the 21st-century.
Jonathan Zittrain, an Internet expert at Harvard Law School, says Twitter is particularly resistant to censorship because there are so many ways for its posts to originatefrom a phone or a Web browserand so many outlets where those posts appear. "The qualities that make Twitter seem inane and half-baked are what make it so powerful," he says.
After Iran's June 12 presidential election, which some opponents say was rigged, President Mahmoud Ahmedinejad was declared the landslide winner over the main opposition candidate, Mir Hussein Moussavi. When protests erupted, Iranian authorities censored many Internet sites, including Facebook, and blocked text messaging on cellphones.
Despite the government crackdown, Iranians used technology like Twitter and YouTube to take matters into their own hands.
One tweet posted in the days after the election read, "We have no national press coverage in Iran, everyone should help spread Moussavi's message. One Person = One Broadcaster."
YouTube was also a critical tool to spread videos when traditional media outlets had difficulty filming the protests or the ensuing crackdown. A cellphone video captured a young Iranian named Neda Agha-Soltan being fatally shot at a protest in Tehran by someone believed to be in a government-backed militia. The videowhich has been viewed on YouTube hundreds of thousands of times, in addition to reaching millions more after it was broadcast on TVhelped galvanize support for the demonstrators.
"We've been struck by the amount of video and eyewitness testimony," says Jon Williams, a news editor at the BBC. "The days when regimes can control the flow of information are over."
China's 'Great Firewall'
New technologies have played a key role in several recent political upheavals. In 2007, the military rulers of Myanmar, also known as Burma, shut down Internet access for several weeks to try to control an uprising. Last year, Chinese authorities blocked access to YouTube amid violent protests in Tibet, so people wouldn't be able to see videos of the police crackdown. And when violence broke out among the Uighur minority in western China in July, authorities blocked access to the Internet and shut down text messaging and international phone service in the region.
Repressive regimes throughout history have had to contend with popular technologiesfrom the printing press and the telegraph to computers and satellite phonesthat made organizing people and transmitting the news easier. In fact, a key factor in the American Revolution was the printing press, which enabled the widespread distribution of political pamphlets that stirred up feelings against England and King George III.
But controlling the Internet and cellphones is a lot harder than censoring newspapers and TV stations or banning printing presses and fax machines, as the Soviet Union and former Communist governments in Eastern Europe did during the Cold War.
And because digital technologies are so critical today to modern economies, repressive governments would pay a high price for shutting them out completely, if that were still possible. China employs tens of thousands of Internet censors to monitor Web postings, and its "Great Firewall" blocks thousands of websitesincluding any search results from Google critical of China's government. Still, China cannot entirely control the Internet, nor is it willing to shut down access and jeopardize economic growth.
According to New York Times columnist Nicholas Kristof, who writes extensively about China, 21st-century technologies could ultimately win out.
"China is not the police state that its leaders sometimes would like it to be; the Communist Party's monopoly on information is crumbling, and its monopoly on power will follow," he says. "The Internet is chipping away relentlessly at the Party."