Pay per click (PPC) campaigns are sometimes confusing. People also refer to it as cost per click (CPC), successful PPC campaigns involves keyword research and good tracking among other things.PPC can be expensive if there is a lot of competition for the keywords. When you're paying for each click to your website, you want to make sure the research has been done. The following may help to explain the differences between the two types of PPC/CPC: flat rate & bid-based.