One balmy May evening, thirty of Silicon Valley’s top entrepreneurs gathered in a private room at the Berlinetta Lounge, in San Francisco. Paul Graham considered the founders of Instacart, DoorDash, Docker, and Stripe, in their hoodies and black jeans, and said, “This is Silicon Valley, right here.” All the founders were graduates of Y Combinator, the startup “accelerator” that Graham co-founded: a three-month boot camp, run twice a year, in how to become a “unicorn”—Valleyspeak for a billion-dollar company. Thirteen thousand fledgling software companies applied to Y Combinator this year, and two hundred and forty were accepted, making it more than twice as hard to get into as Stanford University. After graduating thirteen hundred startups, YC now boasts the power—and the peculiarities—of an island nation.