자료: 구글, 애드워즈 // 광고주 입찰 규칙, 비크리 경매

※ 발췌 (excerpts):

출처 1: Cost-per-click (CPC): Definition

Cost-per-click (CPC) bidding means that you pay for each click on your ads. For CPC bidding campaigns, you set a maximum cost-per-click bid─or simply "max. CPC"─that's the highest amount that you're willing to pay for a click on your ad (unless you're setting bid adjustments, or using Enhanced CPC).

Your max. CPC{https://support.google.com/adwords/answer/6326} is the most you'll typically be charged for a click, but you'll often charged less─sometimes much less. That final amount you're charged for a click is called your actual CPC{https://support.google.com/adwords/answer/6297}.


출처 2: 실제 클릭당비용(CPC): 정의

실제 클릭당비용(실제 CPC)은 클릭에 대한 최종 청구 금액으로, 일반적으로 클릭에 대해 청구되는 최대 클릭당비용(최대 CPC)보다 대부분 낮은 비용(때로는 훨씬 낮은 비용)이 청구됩니다.

애드워즈 입찰에서는 광고 게재순위 및 사이트링크와 같이 광고와 함께 표시되는 광고 형식을 유지하는 데 필요한 최소 금액만 결제하므로 실제 CPC가 최대 CPC보다 낮은 경우가 많습니다. 참고로 향상된 CPC 입찰기능을 사용하거나 입찰가 조정을 설정한 경우 실제 CPC가 최대 CPC를 초과할 수 있습니다.


출처 3: GSP — The Cinderella of Mechanism Design (Christopher A. Wilkens, Ruggiero Cavallo, Rad Niazadeh | Cornell University, Jan 2017)

In February 2002, Google launched its pay-per-click AdWords auction with an innovation that would change the industry: while competitors used a first price model to sell ads on a search results page,[주]1 Google chose a second-price paradigm[문헌28]. The benefits were clear[문헌16], and within 6 years, the search ads industry had standardized on Google's generalized second price (GSP) auction.

There was one problem with GSP: it was not the proper generalization of Vickrey's second price auction, a title that instead belongs to the Vickrey-Clarke-Groves (VCG) mechanism. Google realized this mere months after launch, yet GSP was already humming along, too entrenched to be replaced[문헌28].