What is CPM?

In online marketing and advertising, you'll often hear the term CPM. CPM stands for the cost per one thousand impressions. Banner ads are commonly paid for on a CPM basis. If an advertiser pays a publisher $5 CPM, they are paying that publisher $5 everytime their ad is shown one thousand times.

The CPM model is beneficial to the web publisher because no action is needed by the user for it to generate revenue (e.g. a click or a purchase).