Target users by site
Advertisers will be able to choose site-targeted AdWords campaigns as an alternative, or in addition, to keyword-targeted campaigns. The site targeting option is designed to meet the needs of advertisers who want to place their ads on specific sites in the Google content network. Site-targeted ads run only on sites the advertisers select, based on their judgment of the sites' relevance, reach and appropriateness. These ads do not appear on search result pages.
Keyword-targeted ads will work exactly as they do now. Advertisers choose keywords to help us match their ads to qualified prospects. Keyword targeting enables advertisers to reach new prospects at the precise moment when they're looking for particular products or services. These ads appear on Google.com search results, and advertisers can have them appear on our content and search networks as well.
New max CPM bidding option
With site-targeted advertising, advertisers will simply set a max CPM—that is, the maximum price they're willing to pay for every thousand impressions their ad receives on a particular site. Their ads compete for advertising space on the site with other site-targeted ads as well as with keyword-targeted ads.
Google's technology ensures that advertisers pay no more than the minimum price needed to run an ad on the site. In many cases, they will pay a price lower than their max CPM. This model is different from other CPM (cost-per-impression) models, where advertisers must pay a fixed CPM. Keyword-targeted ads will still follow a cost-per-click bidding model, where advertisers set the maximum price they're willing to pay for each click their ad receives.

