What is Impressions?

Impressions count displays, not people and not attention. One person seeing the same ad five times generates five impressions. An organic listing appearing at the bottom of page two generates an impression even though almost nobody scrolled far enough to see it.

That makes impressions a measure of reach and visibility rather than of interest. They are genuinely useful for spotting changes — a sharp drop in search impressions usually means a ranking or indexing problem, and a sharp rise in profile impressions often follows a category or service change — but they are a diagnostic rather than a result.

The related term is reach, which counts unique people rather than displays, and frequency, which is impressions divided by reach. In a small local market frequency climbs quickly, and a rising frequency with flat results usually means the addressable audience has been exhausted rather than that the campaign is failing.