There are several different counting methodologies in use in the ad tech industry today. Different counting methodologies have varying levels of strictness, with the least strict methods giving credit for impressions with less evidence that they have actually reached users and resulted in valid impressions, and the most strict methods requiring much more certainty before counting an impression as valid.
The Interactive Advertising Bureau (IAB) and the Media Ratings Council (MRC) both recommended measuring desktop and mobile display impressions on a “count on begin to render” basis. The count on begin to render measurement standard means that a buyer’s ad must load and begin to render before an impression is counted as valid. Using this measurement standard brings impression counting methodology closer to counting the actual opportunity for an ad to be seen by a user.
This standard is useful for two key reasons:
To learn about how the count on begin to render methodology is being implemented at AppNexus, see our client FAQ.
For specific information on the standards applied to the counting of viewable impressions, see Introduction to Viewability.
For video ads, an impression is counted when the first frame of the video is loaded. Video reporting often also measures the duration (e.g., first quartile, etc.) of video play. For general information on video concepts, see Introduction to Video Inventory and Formats.