Far from the catchy television spots and sleek magazine spreads are the comparatively modest ads that pop up on websites and in Internet searches. But don't be fooled-online advertising is exploding. Growing at a compound annual rate near 20%, it is now the second-largest advertising channel in the United States. Part history, part guidebook, part prediction for the future, Targeted tells the story of the companies, individuals, and innovations driving this revolution. It takes readers behind the scenes-examining the growth of digital advertising, its enormous potential, and the technologies that are changing the game forever. Leading the way is real-time bidding, which offers advertisers unprecedented precision in targeting ads and measuring their effectiveness. From keyword micro-markets and ad serving systems to aggregated virtual audiences and new business models, Targeted is sweeping in scope and stripped of technical complexity. It is an essential resource for anyone interested in finding and connecting with customers in the vast and shifting Internet universe.