It is a fascinating moment to contemplate. Tech's hottest firm stood at a fork in the road, pondering its future and, being an unusually deliberative company, tried to think through the consequences of each choice. Thanks to the growth of search, Google was capturing bushels of attention, but how to capitalize on that? As we've seen, there have always been two ways of converting attention into cash. The older is to charge admission, as to the spectacle, on the model of the opera or HBO or a book; for Google this would mean licensing or selling access to a premium product. The second is to resell the attention gained, that being the model of the attention merchant.

Tim Wu, The Attention Merchants, loc. 871