Glossary · Platforms and measurement
Viewability
Visibility: that the ad actually had a real chance to be seen on screen.
In detail
An ad can load on a page and never be seen, for example if it sits at the bottom and the person never scrolls down. The most widely used standard (the MRC’s) considers a display ad “viewable” when at least 50% of its pixels were on screen for at least 1 continuous second.
It is expressed as a percentage of viewable impressions. A banner with a clear message and button from the first frame has a better chance of communicating something within that second.
Example
Out of 10,000 impressions, 6,500 were viewable: 65% viewability.