Cost per thousand (CPM) is a marketing metric that measures the cost of reaching one thousand potential customers or viewers through a specific advertising channel. It is calculated by dividing the total cost of an advertising campaign by the number of impressions (views) it generates, and then multiplying that number by one thousand. CPM is commonly used in digital advertising, such as online display ads and social media ads, to determine the effectiveness and efficiency of a campaign. A lower CPM indicates that the advertiser is reaching a larger audience at a lower cost, making it a desirable metric for businesses looking to maximize their advertising budget.