An impression is an event that results when a player is loaded on the page and a video is displayed.

Only some of the pageviews created by your site generate an impression and actually result in the delivery of a campaign; therefore, the number of actual impressions will always be different from that of the pageviews you see on your site's analytics.

​Impressions: the impressions actually recorded by your Units.

The Impressions counted and shown in Reports are those in target with location, device and the end-user profile.