Age: 30
Occupation: Founder and CEO of Groupon
Previous TIME 100 appearances: 0
Andrew Mason is the king of social commerce, the Web's hottest new segment. Groupon offers its passionate subscribers discounts on goods and services if a critical mass of people agree to buy the deals that are e-mailed to them each day. Mason is so confident in Groupon's growth potential that he turned down a $6 billion buyout offer from Google late last year. A competitor, LivingSocial, is threatening to steal some of Groupon's business. But Mason, a music major in college who also started a site that organized collective action around charitable causes ThePoint.com failed to turn a profit but spawned the Groupon model says Groupon may not even be his best idea.