Impressions
The number of times an ad is displayed on a screen, regardless of whether it was actually seen or clicked.
What Impressions means
Impressions count the total number of times an ad is rendered on a user's screen. A single user can generate multiple impressions if they see the same ad multiple times. Impressions are the most basic advertising metric and form the basis for CPM pricing, frequency calculations, and reach analysis. The industry distinguishes between served impressions (the ad was delivered to the page) and viewable impressions (the ad actually appeared in the user's viewport per MRC standards). From a compliance perspective, impression inflation through fraud or policy-violating practices distorts performance metrics. The shift toward viewable impression standards has improved transparency but requires advertisers to understand the difference between served and viewed impressions when evaluating campaign performance.
Related terms
Cost Per Mille
The cost per thousand impressions, a standard pricing model for display and video advertising.
Reach
The total number of unique users who saw an ad at least once during a campaign period.
Frequency
The average number of times a unique user sees a specific ad within a given time period.
Viewability
A metric measuring whether an ad was actually visible to a user, based on industry standards for pixels-in-view and display duration.