Clarification around Pop-Unders
At Google, we value users, advertisers and publishers equally. We have policies in place that define where Google ads should appear and how they must be implemented. These policies help ensure a positive user experience, as well as maintain a healthy ads ecosystem that benefits both publishers and advertisers.
To get your attention, some ads pop up in front of your current browser window, obscuring the content you want to see. Pop-under ads can be annoying as well, as they will "pop under" your window, so that you don't see them until you minimize your browser. We do not believe these ads provide a good user experience, and therefore are not suitable for Google ads.
That is why we recently clarified our policies around pop-ups and pop-unders to help remove any ambiguity. To simplify our policies, we are no longer permitting the placement of Google ads on pages that are loaded as a pop-up or pop-under. Additionally, we do not permit Google ads on any site that contains or triggers pop-unders, regardless of whether Google ads are shown in the pop-unders.
We continually review and evaluate our policies to address emerging trends, and in this case we determined that a policy change was necessary.
As with all policies, publishers are ultimately responsible for ensuring that traffic to their site is compliant with Google policies. To assist publishers, we’ve provided guidance on best practices for buying traffic.