On January 17, 2001, during the impeachment trial of Philippine President Joseph Estrada, loyalists in the Philippine Congress voted to set aside key evidence against him. Less than two hours after the decision was announced, thousands of Filipinos, angry that their corrupt president might be let off the hook, converged on Epifanio de los Santos Avenue, a major crossroads in Manila. The protest was arranged, in part, by forwarded text messages reading, "Go 2 EDSA. Wear blk." The crowd quickly swelled, and in the next few days, over a million people arrived, choking traffic in downtown Manila.

The public's ability to coordinate such a massive and rapid response -- close to seven million text messages were sent that week -- so alarmed the country's legislators that they reversed course and allowed the evidence to be presented. Estrada's fate was sealed; by January 20, he was gone. The event marked the first time that social media had helped force out a national leader. Estrada himself blamed "the text-messaging generation" for his downfall.

Since the rise of the Internet in the early 1990s, the world's networked population has grown from the low millions to the low billions. Over the same period, social media have become a fact of life for civil society worldwide, involving many actors -- regular citizens, activists, nongovernmental organizations, telecommunications firms, software providers, governments. This raises an obvious question for the U.S. government: How does the ubiquity of social media affect U.S. interests, and how should U.S. policy respond to it?

As the communications landscape gets denser, more complex, and more participatory, the networked population is gaining greater access to information, more opportunities to engage in public speech, and an enhanced ability to undertake collective action. In the political arena, as the protests in Manila demonstrated, these increased freedoms can help loosely coordinated publics demand change.