Cost per impression (CPM) is the measured of cost that one will pay when their ad is shown per one thousand impressions. CPM helps to determine other calculations for ads such as CPC (cost per click) and the CTR (click-through rate).
A digital advertiser will bid on the cost cost per (one thousand) impressions before the actual ad is shown. These bids will help to determine if the ad is shown before other ads or it's overall rank in placement.
Why is cost per impression important to marketers?
With any ad campaign, CPM is a vital metric to monitor to find out how effective your ad is.
Cost per impression can help marketers prove return on investment (ROI) for the campaign and potentially your cost per lead.