Cost per click is a kind of pricing model for delivering ads that charges advertisers every time a user clicks on an ad. The formula for calculating CPC is:

CPC = Total Ad Spend ÷ Total Clicks

oCPC refers to optimized cost per click. With oCPC the advertiser's ad is shown to the users most likely to complete an action that is defined by the advertiser as the conversion goal (such as download, purchase, etc.). The advertisers set their bid based on the conversion goal. The advertising platform dynamically calculates CPC based on estimates for CTR and CVR to then show the ad to users that are more likely to complete the action defined as a conversion goal. The platform does this while ensuring that the cost does not exceed the advertiser's bid.