Advertising on search engines now works by charging you a fixed amount every time a user clicks on a "sponsored link" or pay-per-click ad. The price of each click depends on the popularity of the keyword associated with the ad. The total cost of the campaign is the number of clicks times the cost-per-click or CPC.
An advertising payment model where the advertiser pays only when the advertisement is clicked. In other words, the advertiser pays for visitors rather than per advertisement impression. The term CPC (cost per click) is the cost unit.