Cost per Acquisition, also known as Cost per Action and abbreviated as CPA is one of the most common strategies in online marketing. Basically, CPA allows an advertiser to pay for an acquisition of a customer. What this means is that the advertiser will only pay to the publisher once the customer takes action, that is, makes a purchase. The difference between CPC (Cost per Click) and CPA is that in the latter case, the advertiser does not pay each time a visitor clicks on the ad, but only when a conversion is recorded. This enables the advertisers to have a better control of their advertising budget, not to mention that it eliminates the possibility of scams, such as the click fraud.