CPM, cost-per-thousand

CPM, or cost per thousand (the M is from the Roman numeral for thousand, which was derived from the Latin "mille"), is the price an advertiser pays for each 1000 displays of a banner ad.

As opposed to performance-based models such as CPA or CPC, CPM rates guarantee web publishers revenue for each ad displayed, whether the visitor clicks it or not, and are thus usually preferable to CPC or CPA models.

CPM levels at the most common ad networks range from $0.20 - $1.50 for 468x60 banners, up to $5.00 - $8.00 for popups, popunders and layer ads, and potentially higher for interstitials and full page ads.