A week ago, Google Adsense sent publishers an email informing them of the upcoming launch of interest-based advertising and what changes must be implemented in the site’s Privacy Policy.
What is “interest-based advertising”?
It is basically a way for Google advertisers to reach more targeted users by showing ads based on the interests of a site visitor. If a user, for example, watches a lot of music videos on YouTube and visits primarily entertainment sites, Adsense will show more entertainment-related ads to that user, regardless of the site that user is in.