The only true consensus around the standard for viewability is that it's a better metric than only saying whether an ad was served or not.

The current Media Ratings Council definition of a "viewable" ad requires static creative to be at least 50% visible for one second, and videos to be at least 50% visible for two seconds.

But everything from whether publishers should only charge for "viewable" ads to the value of viewability itself is still up for debate.

Watch the new Marketer's Playbook video.