Offer placement targeting to Google AdWords advertisers
You can offer placement targeting to AdWords advertisers so that they can target specific areas of your website. For example, advertisers might select ad units at the top of all publisher site pages or ad units on pages related to entertainment news and sports only. When setting up their campaigns, advertisers can search for placements matching themes and topics they want to target.
You can make your new or pre-existing site placements available to these advertisers at any time.
To set placement targeting for a new or existing placement:
Create a placement or edit an existing placement.
At the bottom of the page, select Google AdWords.
(Optional) To copy targeting settings from an existing AdSense channel, click Copy Adsense targeting.
By selecting Copy Adsense targeting and selecting a channel, you can copy AdSense channel information to your placement and continue to generate revenue from AdWords campaigns that are targeting your site.
Copying AdSense targeting settings will not affect your channels in your AdSense account. However, please note that any channels that you copy will appear twice in your AdSense reports.
Enter a description of your placement (description will be viewable by AdWords advertisers).