CPM, or Cost-Per-Thousand, is a digital advertising pricing model where advertisers pay for every 1,000 impressions of their ad. It is commonly used in display advertising to measure the cost-effectiveness of campaigns based on the cost per thousand impressions. Advertisers specify a set amount they are willing to pay for every thousand ad views. The CPM rate is calculated by dividing the total cost of the campaign by the number of thousands of impressions delivered. CPM allows advertisers to compare costs and plan budgets based on the estimated cost of reaching a specific number of impressions.