Who do you have sex with and why? Is happiness catching? Is wealth contagious? Can your friends make you fat? Why do you bother to vote? Does free will exist? Your friend's friend starts smoking, suddenly you find yourself reaching for a cigarette. But how can someone you'll never know make you fatter, happier and have more sex? This brilliantly original exploration of 'social contagion' examines the power of social networks to influence our behaviour. We like to think that we are largely in control of our day-to-day lives, yet most of what we do, from what we eat to who we sleep with, and even the way we feel, is significantly influenced by those around us - and those around them, and those around them. Our actions can change the behaviours, the beliefs, and even the basic health of people we've never met. In their illuminating account of the pervasive and often bizarre qualities of social networks, pre-eminent social scientists Nicholas Christakis and James Fowler explain why obesity is contagious, why the rich get richer, even how we find and choose our partners. Intriguing and entertaining, with revelatory implications for everything from our notion of the individual to ideas about healthcare and social inequality 'Connected' will change the way you think about every aspect of your life.