The Legacy Builders
Evan Williams (42) and
Biz Stone (40)

CEO of Medium and CEO of Jelly (respectively), San Francisco

Sure, Twitter revolutionized information sharing, but there have been unintended consequences. "There's an increasing amount of noise on the Internet—good information is harder to find," says Evan Williams (pictured, left), one of Twitter's cofounders. "That creates less understanding in the world, not more." Williams and his Twitter cofounder, Biz Stone (right), of course, laid much of the groundwork for the information overload. Before they created the micro-blogging platform, Williams created (and Stone later worked for) one of the first blogging platforms, Blogger, which Google acquired in 2003. Now each has a new start-up that aims to cut through the noise.

Williams launched Medium, a publishing platform and thought-leader publication, in 2012 with the aim of "helping people tell the stories that need to be told and pay attention to the things that need attention." Stone's new venture is Jelly, an app unveiled in January that turns users' Facebook and Twitter contacts into a single network and compels people to answer one another's questions. Investors include Al Gore and Bono.

Biz and Ev, as they're known, are wealthy men thanks to Twitter. They could sit back and dabble with investments and become Silicon Valley grandees—which they basically did for a year or two through Obvious Corp., their investment firm and incubator that helped launch a dozen companies. But reinventing the ways we receive information—for the better—has always been their true purpose. As Williams says, "This was the area where I felt I could have the most impact. At this stage, that's how I measure things."

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The Game Changer
Brandon Beck (31)
CEO of Riot Games, Santa Monica, California

When Los Angeles' Staples Center, the city's premier arena, home of the Lakers, the Clippers, and the Grammys, sold out in near-record time this past fall—under an hour—for something called the League of Legends World Championship, it was a cultural milestone. League of Legends is a video game, and although live "e-sports" have been growing fast around the world (especially in South Korea), this was a wake-up call for anyone who hadn't noticed that gaming has officially ascended from the basement sofa.

Credit Brandon Beck, CEO of Riot Games, LoL's parent company, for a good share of that change. He founded Riot Games, with Marc Merrill, to re-create online the kind of trash-talking fun they had when they used to face off against other gamers in their USC dorm. Launched in 2009, LoL is now the most-played game in the world, a so-called multi-player online battle arena. It's the only game Riot Games makes, it's free, and there's no in-game advertising: The company earns money—a reported $624 million in 2013—on microtransactions (players buying new skins, say) that happen within the game.

And then there's the pro league, in which competitions are broadcast and people log on just to watch others play. The championship at the Staples Center included confetti cannons and NFL-style color commentators. Thirty-two million people watched online, 8.5 million of them live. (By comparison, 19 million watched the final game of the World Series this past year.) Beck sees in those metrics a happy corollary: game geeks coming out of their shells. "To see a bunch of people who never really learned how to cheer at a sports event—to see them find that energy so naturally? That's just awesome."

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The Eraser
Evan Spiegel (23)
CEO of Snapchat, Venice, California

Not since Mark Zuckerberg has an emerging tech titan inspired more sniping than Snapchat CEO Evan Spiegel, 23, the product of a privileged Los Angeles upbringing who, last November, reportedly turned his nose up at a $3 billion acquisition offer from Facebook, then a rumored $4 billion from Google. (The chutzpah!) Spiegel launched Snapchat, an app that allows users to send photos, videos, and texts that self-destruct in 10 seconds or less, with Bobby Murphy in 2011, when they were at Stanford. The company has since attracted $123 million in venture capital and the stink eye from people who write it off as little more than a tool for sexting.

But to dismiss Snapchat is to misunderstand the change in the Zeitgeist that Spiegel anticipated: a retreat from the everything-for-the-record world that Facebook represents. "The entire architecture of the Internet has been about storing information," Spiegel says. "We believe communication needs a different framework, where you delete everything except what's important." That's more like real-life conversation than Facebook is, which helps explain why teens have been eschewing the giant in favor of Snapchat. Zuckerberg went so far as to create a copycat, Poke, but it flopped.

Today, Spiegel says, nearly half of Snapchat's users, who send 400 million snaps per day, fall outside the 12-to-25 age range. As millions more people come around to Spiegel's way of thinking, the idea that the app is a passing fad is fading. Privacy fears in the era of revenge porn and helicopter parenting are real, after all. "Anything you say can be taken out of context and shared with millions of people," Spiegel says. But not on Snapchat.