Cost-Per-Impression (CPI) is a digital advertising metric that measures the cost an advertiser pays for each time their ad is displayed, regardless of whether it is clicked. This metric helps businesses understand the effectiveness of their advertising campaigns by evaluating how many times their ads are seen by potential customers. Advertisers often use CPI to compare the performance of different ad placements and platforms. By analyzing CPI, businesses can make informed decisions about where to allocate their advertising budgets to maximize visibility and reach their target audience effectively.