You are hereAdsense Section Targeting
Adsense Section Targeting
Section targeting allows you to suggest sections of your text and HTML content that you'd like us to emphasize or downplay when matching ads to your site's content.
https://www.google.com/adsense/support/bin/answer.py?answer=...
<!-- google_ad_section_start -->
the important part of your content
<!-- google_ad_section_end -->
<!-- google_ad_section_start(weight=ignore) -->
irrelevant content
<!-- google_ad_section_end -->
