The jpoc guide Website advertising income for small websites
The cost per click or cpc
Unlike CPM this is a particularly internet term although it is not a model unique to the internet. It stands for Cost Per Click. Under this system, an advertiser pays nothing to have ads displayed on a website but instead, pays a fee every time that a surfer clicks on their ad. Now clearly, the amount of money that a webmaster can receive on this scheme will depend on the number of clicks rather than on the number of unique page views. This important number is the number of page views multiplied by the Click Through Ratio or CTR.
CPC normally pays webmasters between ten and twenty cents per click but I have seen some quotes as low as one cent and as high as seventy.
CPC ads are in general, easier for small sites to sign up for. The main reason is that advertisers and agencies want clicks and the more times that an ad is shown, the more clicks they will get. If an agency is being paid for clicks then it is in their interest to maximise the number of times that an ad is seen.
Of course, this does not guarantee that you will be accepted by a CPC agency. Some clicks may be worthless. For example, an advertiser selling mortgage services will not want any clicks at all from a site catering to teenage girls. Also, it does cost an agency to deliver banners and if your site has a very low CTR, it is not worthwhile to serve you with banners.
Actually, there is nothing "wrong" with CPC advertising. It can make good money for webmasters and, if advertisers want to get clicks, why should they not pay for them? In any case, a mix of CPM and CPC advertising is a good thing for webmasters. You can tuck the CPC ads away at the bottom of your pages and have CPM as at the top. The CPM advertisers will be happy because their banners will get maximum exposure but the CPC folks will get a good deal too if their ads are on view when a visitor has finished reading your page and is about to click for another destination.