What's the connection between teen smoking, the midnight ride of Paul Revere, the continued popularity of Hush Puppies shoes, and "Six Degrees of Separation from Kevin Bacon"? Just as a single sick person can start an epidemic of the flu, so too can a small but precisely targeted push cause a fashion trend, the popularity of a new product, or a drop in the crime rate. Finding links between an astonishing range of subjects, Malcolm Gladwell suggests that three categories of people—Connectors, Mavens, and Salesmen—spark that magic moment when an idea or social behavior crosses a threshold and spreads like wildfire.