What is CPI?

CPI, cost per impression. This term is associated with online traffic and internet advertising. It refers to the price paid by an advertiser for each impression of their ad to an internet user. A similar term associated with cost per impression is CPM, cost per mille, which is the cost per thousand impressions. These terms are used to determine the effectiveness and profitability of online advertising. Advertising in other media, such as radio or television, is paid for in a similar way. Advertising is sold based on an estimate of the number of viewers or listeners.