Cost Per Mille (CPM) is a marketing term that refers to the cost of reaching one thousand impressions of an advertisement. It is commonly used in online advertising to measure the effectiveness and pricing of ad campaigns. Advertisers pay a set fee for every thousand times their ad is displayed, regardless of whether users click on it. CPM helps businesses evaluate the cost-effectiveness of their advertising strategies. By comparing CPM rates across different platforms, advertisers can determine where to allocate their budgets for maximum visibility and engagement. This metric is essential for optimizing advertising efforts and achieving desired outcomes.