CPM, or Cost per Mille, or Cost per thousand impressions (mille is the latin word for thousand) is one of the most common ways to purchase advertising today. Though it is used across many branding and direct response campaigns, it is particularly suited for verticals and campaigns intended to raise awareness.
For instance, if the CPM is priced at $2, and you wish to deliver 1,000,000 impressions, then the cost of the campaign is
(Total # of impressions / 1000) * $2
(1,000,000 impressions / 1000) * $2 = $2,000
Many advertisers running direct response or performance campaigns who pay for media based on CPM will often calculate an eCPC or eCPA as a KPI in order to track their success and to optimize toward lowering that KPI.
