CPM stands for "Cost Per Mille" or "Cost Per Thousand." It's a metric used in advertising and marketing to denote the cost of reaching a thousand people (or, in Latin, "mille" means thousand) with a specific advertisement or message. CPM is commonly used in the context of online advertising, especially for display ads, video ads, and other forms of digital advertising.

Here's how it works: Let's say an advertiser wants to run a display ad campaign and the cost is $2 CPM. That means the advertiser pays $2 for every thousand times the ad is displayed, regardless of whether anyone clicks on it or takes any action.

CPM is often used as a benchmark for comparing the relative cost-effectiveness of different advertising campaigns or platforms. Advertisers use CPM to evaluate and compare the cost of reaching a thousand potential customers across various advertising channels to make informed decisions about where to allocate their advertising budgets for maximum impact.

Keep in mind that while CPM is useful for comparing costs across different channels, it doesn't measure the effectiveness of an ad in terms of user engagement or conversion rates. Other metrics like Click-Through Rate (CTR), Conversion Rate, Return on Investment (ROI), etc., are also crucial for evaluating the overall performance of an advertising campaign.

https://simplified.com/social-media-glossary/cpm