The 2008 TIME 100

The internet is about people connecting to people, whether for business, politics or socializing. That's something we've all been doing since long before the Internet existed. The real accomplishment is to make those connections so versatile and different that they create a social network that not only reflects your life but maybe expands it.

Mark Zuckerberg, 23, the creator of Facebook, has done just that.

Working from his dorm room at Harvard in 2004, Zuckerberg launched Facebook as a campuswide system and later expanded it to other colleges. The site exploded nationally and globally, and with that came tens of millions of dollars from investors, buyout offers from Yahoo! and Viacom, and a worldwide community of Facebook users.

All that happened because Zuckerberg has remained true to his vision, focusing on building a community rather than on a mere exit strategy—which is why those buyout offers have been declined. Facebook also provides a flexible information ecology, offering a fairly open system that allows users to add small applications to pages. As a result, members are starting to run businesses via the Facebook platform, including loan systems and music distribution. There are challenges, including "Facebook fatigue," which results from just too many invitations. Then, of course, there are issues related to monetization; investors are patient, but not forever. Facebook, however, just keeps growing, with more than 70 million active users so far. That's a lot of people connecting via Zuckerberg's vision—which is just what that vision was always about.

Newmark is the founder of Craigslist, which attracts 30 million people a month