The acronym “CPC” stands for “Cost Per Click.” In the world of Internet advertising, “Cost Per Click” is the price you are willing to pay for each person who visits your website and then clicks on one of your ads.
“CPM” stands for “Cost Per Thousand.” It’s the same as “CPC” except it’s a different unit of measurement. What it means is that instead of paying for each click, you are willing to pay for every 1,000 impressions your ad receives.
“CPA” stands for “Cost Per Action.” It’s similar to “CPC” in that it’s another way of measuring the success of your Internet advertising (conversions).