Quote from the article:
For example, Google may automatically assume a customer is interested in cars because the customer surfs car forums a lot. Therefore, Google will provide car ads on AdSense ads to the customer. However, the customer can change its ad preferences and even requires Google to provide other categories of ads.
some people may say, they don't want ads at all. I always hear that, and if you then look in their home you will see they love brands as we all do. Ads are not evil, they are useful, because - if done well - they give your real good information, or at least linking emotions to a product. Yes, people feel better if they see a parfume ad, even if they don't recognize that.
So, personalized ads where you have kind of control are just good. And imagine how effective!