Placement-targeted Advertisements (formerly Site-Targeted Advertisements)
In 2003 Google introduced site-targeted advertising. Using the AdWords control panel, advertisers can enter keywords, domain names, topics, and demographic targeting preferences, and Google places the ads on what they see as relevant sites within their content network. If domain names are targeted, Google also provides a list of related sites for placement. Advertisers may bid on a cost-per-impression (CPM) or cost-per-click (CPC) basis for site targeting.
With placement targeting, it is possible for an ad to take up the entire ad block rather than have the ad block split into 2 to 4 ads, resulting in higher visibility for the advertiser.
The minimum cost-per-thousand impressions bid for placement-targeted campaigns is 25 cents. There is no minimum CPC bid, however.
Read more about this topic: AdWords