Google AdSense has introduced two new “page-level” ad formats that only display on high-end mobile devices. The new formats are considered beta at this time. The new formats are anchor/overlay ads and vignette ads. Google explains that the new formats do not count towards your 3 ads/page limit and are optimized to help increase revenue for mobile-optimized sites.
Anchor ads are mobile display ads that stick to the bottom edge of the screen. Users can easily dismiss them at any time by dragging the slider to the bottom.
To enable the use of these new ad formats, it is controlled from the Google AdSense dashboard under ‘My Ads’. There is a new option under Content for Page-level ads (beta). On this page you can selectively enable one or both of the new formats by simply clicking the toggle switch.
Once the code is pasted in and your site cache is cleared, you can test the ads by going to yoursite.com/#googleads on a mobile device. This will open a pop-up layer and allow you to test the ad formats and see how they look on your site. It will give you a report for why the ads might not show up, such as being disabled in AdSense, using an unsupported browser, or the viewport being too large.