Google has taken another positive step in trying to help reign in the mess of annoying ads on website.

Google will no longer permit placing pop-up or pop-under ads, the company declared in a blog post. They also won’t allow the use of any Google ads on sites that contain or trigger pop-unders.

“We do not believe these ads provide a good user experience, and therefore are not suitable for Google ads,” the company said.

In its updated clarification on policies, Google said “…sites using AdSense may not be loaded by any software that triggers pop-ups, modifies browser settings, redirects users to unwanted sites, or otherwise interferes with normal site navigation.”

Here’s a link to Google policies and to best practices for buying traffic.