← Glossary
What are impressions?
An impression is a single instance of your ad being shown — one person seeing it three times is three impressions.
The distinction from reach is the one that trips people up. Reach counts people; impressions count showings. Ten thousand impressions across two thousand people means the average person saw your ad five times.
That ratio is frequency, and it's where impressions become useful. A high impression count against a small audience means you're showing the same ad to the same people repeatedly, which is the mechanism behind ad fatigue.
Impressions are also the unit Meta charges against, which is why small budgets still deliver there: you're buying showings, not clicks.