What does ‘impression’ mean in online advertising?

In online advertising, an "impression" refers to the count of how many times an ad is served to a user's device, regardless of whether the ad is clicked or interacted with. This metric is crucial for advertisers because it measures the potential visibility of an ad; each impression represents an opportunity for a user to see the advertisement. Advertisers use impressions to assess the reach of their campaign and to determine the effectiveness of their messaging in terms of exposure.

Understanding impressions helps advertisers optimize their campaigns, as they can analyze which ads garner more visibility and refine their strategies accordingly. While it is important to note that impressions do not equate to engagement (as clicks or conversions would), they are foundational to evaluating the performance of display ads and the overall impressions can correlate with brand awareness and recognition in the marketplace.