Thousands of Africans head to China each year to buy cell phones, auto parts, and other products that they will import to their home countries through a clandestine global back channel.

Hundreds of Paraguayan merchants smuggle computers, electronics, and clothing across the border to Brazil. Scores of laid-off San Franciscans, working without any licenses, use Twitter to sell home-cooked foods. Dozens of major multinationals sell products through unregistered kiosks and street vendors around the world. When we think of the informal economy, we tend to think of crime: prostitution, gun running, drug trafficking. Stealth of Nations opens up this underground realm, showing how the worldwide informal economy deals mostly in legal products and is, in fact, a ten-trillion-dollar industry, making it the second-largest economy in the world, after that of the United States.