What does 1,000 ad impressions or CPM mean?

An “impression” is a metric that quantifies the display of an ad on a web page or inside a mobile app. Impressions are used in banner, native, search, and video advertising.


Paying per impression is the most common way to pay for display advertising on carsales. And to simplify the sheer volume of ads bought (which is often in hundreds of thousands or millions) they are measured by "CPM" (Cost Per Mille) where 'mille' refers to 1,000 impressions.


'Impressions' and 'CPM' are both standard definitions across the global advertising industry.



Technically, an impressions is defined by the Interactive Advertising Bureau (IAB) trade group as “a measurement of responses from a Web server to a page request from the user browser”. It contrasts to the more specific metric ‘Viewable Impression’ which also verifies that over 50% of the ad pixels were in-view of the user’s screen for at least 1 second (or 2 seconds, for video).


For more industry terminology, please refer to our Glossary of Terms.

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