The cost-per-click (CPC) is the amount you earn each time a user clicks on your ad. The CPC for any ad is determined by the advertiser; some advertisers may be willing to pay more per click than others, depending on what they’re advertising.
CPM stands for “cost per 1000 impressions.” Advertisers running CPM ads set their desired price per 1000 ads served and pay each time their ad appears.
As a publisher, you’ll earn revenue each time a CPM ad is served to your page and viewed by a user. CPM ads compete against cost per click (CPC) ads in our ad auction, and we’ll display whichever ad is expected to earn more revenue for you.
How to earn with AdSense for search
AdSense for Search AdSense for search lets you offer your users Google web search directly from your pages. By placing an AdSense for search box on your site, you’ll generate earnings from ad clicks made by users on the search results pages.
You won’t, however, receive revenue from user searches through your AdSense for Search box. When users perform searches on your site, but choose not to click on the ads on the search results pages, you will not receive any earnings.