What is ad engagement?

In mobile advertising, ad engagement refers to whether users are seeing and interacting with a mobile ad creative. 

The metrics by which engagement is measured can vary based on the goals of a given campaign and the type of ad being displayed, such as whether a user clicks a static mobile creative, or whether a user watches a video creative to completion without closing the app or pressing skip. 

For example, if a video ad creative runs 1000 times, the engagement measure of choice is watching the video to completion rather than skipping, and 100 users watch the video all the way through, the engagement rate for the creative would be 100/1000, or 10%