What is Cost per Thousand (CPM)?Abbreviated as CPM (the letter "M" in the abbreviation is the Roman numeral for one thousand). CPM is used by Internet marketers and mobile advertisers to price ad banners. Sites that sell advertising will guarantee an advertiser a certain number of impressions (number of times an ad banner is downloaded and presumably seen by visitors), then set a rate based on that guarantee times the CPM rate.
Media planners calculate CPM to estimate the efficiency of a campaign and to compare the costs of various media. But in order to be reasonably accurate, the comparison must involve media that reach roughly the same audience.
Other methods of pricing website advertising include cost per click (CPC), where the advertiser pays each time a website visitor actually clicks on the ad, and cost per acquisition (CPA), where the advertiser only pays each time a website visitor makes a purchase that can be directly traced to having clicked on that ad.