How does Google target ads to my website?
Google automatically delivers ads that are targeted to your content or audience. We do this in two ways:
- Contextual targeting
Our technology uses such factors as keyword analysis, word frequency, font size, and the overall link structure of the web, in order to determine what a webpage is about and precisely match Google ads to each page.- Placement targeting
With placement targeting, advertisers choose specific ad placements, or subsections of publisher websites, on which to run their ads. Ads that are placement-targeted may not be precisely related to the content of a page, but are hand-picked by advertisers who’ve determined a match between what your users are interested in and what they have to offer.
From the Google AdSense support website.