cost-per-click
An advertising model where the advertiser pays only when someone actually clicks the ad, not when it is merely shown.
Cost-per-click, usually shortened to CPC, is the pricing model that built Google’s advertising business. The alternative is paying per thousand times an ad appears, which rewards putting ads in front of as many eyes as possible. CPC instead rewards putting them in front of the right eyes, because an ad nobody clicks earns nothing.
This matters now because AI chatbots are adopting it. OpenAI moved ChatGPT’s ads to a cost-per-click model in April 2026. The shift changes the incentive inside the product: an assistant paid per click has a reason to place recommendations where you are most likely to act on them, which is precisely where they are hardest to tell apart from genuine advice.