Meet the Disruptors of the TIME 100

The Time 100 has featured its fair share of tech world disruptors, from Bill Gates to Steve Jobs to Mark Zuckerberg. This year is no different, with an impressive array of tech CEOs that range from a couple of Chinese mega-moguls to a pair of fresh-faced innovators fresh out of Stanford University. Here’s a breakdown of the people on this year’s list who are doing the most to change the world of technology:

Evan Spiegel and Bobby Murphy

Ages: 23 and 25

What they did: Launched the messaging app Snapchat, through which users send each other pictures that disappear after a few seconds. The app is changing the way we communicate—or at least, the way your kids communicate. The rapid growth of the app, which processes 400 million photos per day, is the latest sign that people are craving ways to connect through private networks online instead of broadcasting all their thoughts to their Facebook friends.

Who’s scared of them: Facebook, which offered to buy Snapchat for $3 billion last fall and got turned down. The company also launched a Snapchat clone called Poke, which flopped.

Pony Ma

Age: 42

What he did: Founded Tencent, the giant Chinese Internet company that runs everything from social networks to massive multiplayer online games. At more than $150 billion, its market capitalization eclipses large American tech firms like Intel and Hewlett-Packard.

Who’s scared of him: The Chinese government, whose strict censorship laws are harder to enforce on private messaging services like Tencent’s WeChat app. The government has forced WeChat to restrict certain words, but users can still communicate through images and audio in ways that are tough to regulate.

Tony Fadell

Age: 45

What he did: Known as the “father of the iPod,” Fadell spearheaded the development of Apple’s disruptive music device. Later, he launched the smart smoke detector company Nest, which was bought by Google for $3.2 billion at the start of the year.

Who’s scared of him: Well, smoke alarm manufacturers, obviously. More broadly, though, Nest and other companies that are developing products tied to the “Internet of Things” could threaten the manufacturers of all sorts of traditional appliances, from televisions to refrigerators to automobiles.

Jeff Bezos

Age: 50

What he did: What didn’t he do? Bezos’s Amazon began as an online book store and is now a grocery store, a music retailer, an entertainment company, a fashion outlet, and a web hosting service that keeps much of the Internet online. Most recently he entered the journalism business by buying the Washington Post for $250 million.

Who’s scared of him: Physical retailers like Wal-Mart, of course, but also a growing a number of his tech peers. Next on his list of targets may be Apple—Amazon is rumored to be launching a smartphone to compete with the iPhone later this year.

Jack Ma

Age: 49

What he did: Created the Chinese giant Alibaba, the biggest e-commerce company in the world. The company runs a merchant marketplace like eBay and an online payments service like PayPal, as well as a cloud computing service and other businesses. Its public offering in the U.S. later this year could be bigger than Facebook’s and bring an onslaught of Chinese tech firms to American shores.

Who’s scared of him: Probably everyone. Like Amazon, Alibaba has its hand in a lot of different businesses, and it’s increasingly making big investments that operate outside of China. For example, the company invested $215 million in a messaging app called Tango that is competing in the same sector as WhatsApp.

Travis Kalanick

Age: 37

What he did: Launched the upscale, on-demand taxi service called Uber, then expanded its appeal to the masses with a cheaper ride-sharing program.

Who’s scared of him: Traditional taxi companies, which have tried to claim that Uber’s service is illegal. Soon it may be FedEx or the U.S. Postal Service complaining—Uber is testing a new courier service in New York right now.