Cost-per-impression (CPM) is a digital advertising metric that measures the cost of displaying an ad to 1,000 viewers. Advertisers use CPM to assess the efficiency of their ad campaigns, as it helps them understand how much they are spending to reach a specific audience. This metric is particularly useful for brand awareness campaigns where the goal is to maximize visibility rather than immediate sales. In a CPM model, advertisers pay a set fee based on the number of impressions their ads receive, regardless of whether users click on the ads. This approach allows businesses to budget effectively and optimize their advertising strategies based on audience reach and engagement.