Ten years ago the idea of getting into a stranger's car or walking into a stranger's home would have seemed bizarre and dangerous, but today it's as common as ordering a book online. Uber and Airbnb have ushered in a new era: redefining neighborhoods, challenging the way governments regulate business, and changing the way we travel. In the spirit of iconic Silicon Valley renegades like Steve Jobs and Bill Gates, another generation of entrepreneurs is using technology to upend convention and disrupt entire industries. These are the upstarts, idiosyncratic founders with limitless drive and an abundance of self-confidence. Led by such visionaries as Travis Kalanick of Uber and Brian Chesky of Airbnb, they are rewriting the rules of business and often sidestepping serious ethical and legal obstacles in the process.