Chris Hughes is having a philosophical moment. "I don't really know what 'community' means. And I never use that word."

We are in Washington, D.C., just three days before his most recent boss, Barack Obama, will take office. It is so bone-jarringly cold that even nestled over coffee inside a Starbucks, we can see our breath. I resist the urge to pat his nearly whiskerless cheek, or reach over to tighten his jacket against the frigid air. Such a baby face. But at the age of 25, Hughes has helped create two of the most successful startups in modern history, Facebook and the campaign apparatus that got Barack Obama elected. Both were dedicated to the proposition that communities, and the way we share and interact within them, are vitally important. As he recounts his two years as director of online organizing for the man who put community organizing on the map, the existential reverie is understandable. He doesn't know what community means? Really? "Well, I just never think of myself as being in the business of building an online community."

Hughes is a technology star whose business is people. At Facebook and in the Obama campaign, he has been plowing what he observes about human behavior into online systems that help real people do what they want to do in their real lives. He helped develop the most robust set of Web-based social-networking tools ever used in a political campaign, enabling energized citizens to turn themselves into activists, long before a single human field staffer arrived to show them how.

"Technology has always been used as a net to capture people in a campaign or cause, but not to organize," says Obama campaign manager David Plouffe. "Chris saw what was possible before anyone else." Hughes built something the candidate said he wanted but didn't yet know was possible: a virtual mechanism for scaling and supporting community action. Then that community turned around and elected his boss president. "I still can't quite wrap my mind around it," Hughes says.

His key tool was My.BarackObama.com, or MyBO for short, a surprisingly intuitive and fun-to-use networking Web site that allowed Obama supporters to create groups, plan events, raise funds, download tools, and connect with one another -- not unlike a more focused, activist Facebook. MyBO also let the campaign reach its most passionate supporters cheaply and effectively. By the time the campaign was over, volunteers had created more than 2 million profiles on the site, planned 200,000 offline events, formed 35,000 groups, posted 400,000 blogs, and raised $30 million on 70,000 personal fund-raising pages.

There were, of course, many players in the Obama victory, starting with the candidate himself. President Obama was not made available for an interview (not surprising given his new set of responsibilities). But Plouffe, sounding very much like the jubilant CEO of a super-successful startup, is clear: "We were very lucky that Chris gravitated to the campaign early." Indeed, a close look at Hughes's efforts and their impact on the campaign sheds new light on Obama's success at the polls -- in both the primary and the general elections -- and offers lessons for any enterprise seeking to tap social networking as a tool.

At first, online organizing was a stepchild within Obama's new-media operation. But after the loss in the New Hampshire primary, the volunteer networks that Hughes had built with his bare-bones staff "became critically important," says Plouffe. "When we turned to the community, they were there. We sent staff into Colorado and Missouri for caucuses, and the staff was already half-organized." The theme of the campaign, direct from Obama, was that the people were the organization. "We were there to support the people," Plouffe continues, "but that simply would not have been possible if we did not have a set of online tools that enabled us to do that. It wasn't just a tactic. Chris made that happen."