To get these going, publishers place one piece of code on all the pages that will display ads.
The first version of AdSense Anchor ads — also called overlays ads — launched in 2013, though they have evolved quite a bit from that first version. The ads are anchored to the edge of the user’s screen, but they can be dismissed.
Vignette ads, like intersitials, are full-screen ads. Unlike traditional interstitial ads, though, Vignettes display when a user leaves rather than arrives on a page. These ads will only show a limited number of times per user.
Ads in both formats will not count toward the three-ads-per-page limit and will only serve on mobile-optimized web pages displaying on smartphones. Google says Anchor and Vignette ads are just the first of many Page-level ad formats to come.
For more details and instructions on how to get started, see the AdSense video on Page-level ads below.