[...] By rewarding advertisers who can successfully predict the keywords that users type in and by punishing those who cannot, Google hopes that AdWords can be relevant and useful to online search.

Nevertheless, AdWords is only profitable because it is a vertically integrated system in which Google controls every step of the process by providing search results to users, by selling "keywords" to advertisers, and by providing statistics to marketers. [...]

Despite Google's claims, a vertically integrated advertising system may not be that objective because it is difficult to determine what the exchange value of keywords is. [...] Internet search creates unlimited time because millions of searches take place at any given moment even though only a small number of users see the same ads. In addition, keywords are not exclusive; a number of advertisers can bid for the same keywords. Because of the non-exclusivity and non-scarcity of keywords, their exchange value should be very low, if not close to zero. This is clearly not the case for Google ads [...]

The concept of the audience commodity is crucial to understanding why Google is able to charge advertisers for keywords even though they are neither exhaustive nor exclusive. [...] the exchange value of the audience commodity is imaginary.