Behavioral targeted advertising

A light overview of personalized advertising at Search Engine Journal. A couple excerpts:

Sites visited, content viewed, and length of visit are .. analyzed to predict an online behavioral pattern for such a user ... Behavioral ad networks then serve targeted advertising related to that user's behavioral classification ...

According to some recent studies, behavior-based ads are faring much better than content-placed ads ... [In one example], when compared with the basic web ads, the behavior ads were seen by 115 percent more business travelers making at least one trip a year. The targeted consumers also scored three percent higher than the average viewers in brand awareness ... Because behavioral marketing enables advertisers to more easily determine and then postulate about user preferences and purchasing habits, the advertiser is able to treat each prospect more as an individual than an advertising collective.

Rather than blast a broad audience with your ad, you target just the people who might be interested. Personalized advertising is more effective because it is more relevant and useful to customers.

The article only describes the more common profile-based approach to personalized advertising, but there's many other techniques that could work well on this problem.