"Twitter seems like a perfect start-up success story. In barely six years, a small group of young, ambitious programmers in Silicon Valley built an $11.5 billion business out of the ashes of a failed podcasting company. Today Twitter boasts more than 200 million active users and has affected business, politics, media, and other fields in innumerable ways. Now Nick Bilton of the New York Times takes readers behind the scenes with a narrative that shows...