Digital marketing term
Ad Impression
One serve of an ad unit onto a screen, with no promise that it was noticed or clicked. CPM and click-through rate both use this raw count as the base.
Detailed explanation
An impression fires when the creative is served onto the screen. It is the denominator for CPM and CTR in display, video, and social. Five serves to the same person are five impressions; reach is a different metric.
A raw impression is not a view. Viewability (for display, typically 50% of pixels in the viewport for one continuous second) and invalid-traffic filters exist because served-but-unseen inventory is cheap for a reason. Bots and stacked units inflate a low CPM.
Read impressions with reach and frequency. CPM alone is not quality. Look at viewable, valid serves, then clicks or conversions. Uncapped cheap impressions are fatigue, not scale.
Frequently asked questions
- Does an impression mean someone saw the ad?
- No. It means it was served. Viewability measures whether enough of the ad actually sat in the visible viewport.
- Why track reach separately from impressions?
- Impressions count repeats. Reach counts distinct people. Frequency is roughly impressions divided by reach.
Related terms
Internal links for the topic cluster — read these concepts together.
- ImpressionAn impression is a single instance of an online ad being displayed to a user.
- CPMCPM (Cost Per Mille) is the cost of 1,000 ad impressions; it is one of the most common media buying units.
- CTRCTR (Click-Through Rate) is the percentage of impressions that result in a click on an ad or link.
- ClickA tap or press on an ad or link; opening the page and converting are separate events. Click-through rate is this count divided by impressions.
- ViewA video or ad counted as watched or seen once it clears the platform’s threshold — not the same as an impression. YouTube, Meta, and programmatic clocks differ, so do not treat the totals as identical.
- Display AdvertisingBanners, native units, and other visual formats on sites and apps. Unlike search text ads, they show up before someone has typed a query into the box.