Impression
One served ad opportunity you were billed for, at the grain the report defines. Not a viewable impression unless a vendor measured it.
Published 2026-09-09 · Search job: what is an ad impression
An impression is a served ad counted by the exchange report. You pay CPM against those counts. It is the denominator for CTR and for a strict IVT rate.
It is not automatically a viewable impression. Viewability requires a vendor measurement on the creative. Until that tag is attached, viewable_impressions can return zero because nothing is measuring, not because nobody saw the ad.
It is also not a click and not a visit. Most remnant impressions do nothing visible in a click column. Our August 2026 Supply Bench pull found 93.4 percent of placements with zero clicks. That is normal leftover inventory, not a creative that "failed" in the search-ads sense.
Two spend sources can cover the same impressions (hourly rows and a lifetime snapshot). Do not sum them. The product reads the greater of the snapshot and the non-snapshot sum.
When you judge quality, keep impressions, invalid impressions, clicks, and visits as separate columns. Start from how to judge display traffic.