The concept is simple enough. In the source code for your Web page, just wrap comments around the content you want the ads to pick up on like this:

<!– google_ad_section_start –>
Your good content here
<!– google_ad_section_end –>

You wrap the content you want ignored by Adsense in comments like so:

&lt!–google_ad_section_start(weight=ignore)–>
Your bad content here
<!– google_ad_section_end –>

For more info check out Google’s Adsense Help Center article on section targeting.

In this way you can suggest to Google which content you want your Adsense ads to target, and which you want them to ignore. So the next time my blog is crawled, I’m looking for a sidebar without Christmas tree ads. That will be my Christmas present from Google.