Impression
An impression is one instance of an ad, listing, or message being displayed, whether or not anyone engaged with it.
What an impression is
An impression is one instance of something being shown: an ad rendered in a feed, a listing appearing on a results page, an email landing in an inbox.
Shown, not necessarily seen. The count includes renders the person scrolled past or never reached.
Why impressions matter
Impressions are the denominator. Click-through rate, cost per thousand, and share-of-voice math all start from how many times the thing appeared.
Movement in impressions also signals reach itself: rankings gained or lost, ad delivery throttled or expanded, before clicks change at all.
How impressions are counted
- Ads: counted when the ad renders, with viewability standards for stricter counting
- Search: counted when the listing appears on a viewed results page
- Email: opens are the closest equivalent, with known accuracy limits
- Social: counted per display in a feed, including repeats
Frequently asked questions
Impressions vs reach: what’s the difference?
Impressions count displays; reach counts unique people. One person seeing an ad five times is five impressions, one reach.
Are impressions worth optimizing for?
As a diagnostic, yes; as a goal, rarely. Impressions without clicks and conversions behind them measure presence, not progress.