Impressions

Impressions in ads reporting — served vs viewable, and denominators for CPM/CTR.

MetricsCross-platform

An impression is counted when an ad is served and enters the measurable viewport (platform rules differ on viewability thresholds). Impressions are the denominator for CPM and CTR; rising impressions with flat clicks usually means creative or audience fatigue, not “more reach for free.”

Viewable impressions (Active View, etc.) may be lower than served impressions — compare metrics apples-to-apples in reporting.

Sources

IAB →

Related terms

Cost per mille (CPM)
Click-through rate (CTR)
Frequency

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