At what cost revenue?

It's an oft-seen question from publishers: Are we earning revenue for ad impressions or for ad clicks? The answer is that it depends on whether cost-per-impression (CPM) ads or cost-per-click (CPC) ads are appearing on your pages. By default, CPC ads will show on your site and you'll generate earnings for valid clicks on those ads. However, your ad units will display CPM ads when advertisers bid specifically on your site using site targeting, and for those ads you'll generate earnings with each valid impression. Please keep in mind that CPM earnings are not the same as the values you see in your eCPM column; your eCPM is only a reporting feature that can help you compare ad performance।

To determine which type of ad you displayed on specific days, you can follow these instructions to generate a report। In your Advanced Reports, the ad type 'Site' refers to CPM ads, and 'Contextual' refers to CPC ads.

Want to show more CPM ads on your site? It's not possible to request CPM ads, but you can help advertisers get interested in your site by customizing your Onsite Advertiser Sign-up landing page. Advertisers can then create campaigns targeted specifically at your site, directly from your site. And don't forget to focus on quality, placement, and size -- take a look at some important tips from the AdWords team on what advertisers look for in site targeting their CPM ads।

Remember: keep publishing that high-quality content and the advertisers will come to you.

Source: Google Inside AdSense Blog