Most of us have had the experience of running into a friend of a friend far away from home - and feeling that the world is somehow smaller than it should be. We usually write off such unlikely encounters as coincidence, even though they seem to happen with uncanny frequency. According to some physicists, it turns out that this 'small-world' phenomenon is no coincidence at all. Rather, it is a manifestation of a hidden and powerful design that binds the world together. The Internet, the brain, power-grids and the global economy are all networks that seem to have evolved a 'small-world' geometry - with properties independent of the nature of the things themselves. SMALL WORLD argues that this underlying pattern may be one of nature's greatest design tricks, and the book shows us how scientists are putting this new insight to work.