Cost Per Action or CPA (sometimes known as Pay Per Action or PPA) is an online advertising pricing model, where advertiser pays the publisher when end user / visitor perform a certain action or a sequence of actions (Such as a purchase, a form submission, a sign-up etc) related to the advertisement.

The CPA can be determined by different factors, depending where the online advertising inventory is being purchased.

CPA is sometimes referred to as "Cost Per Acquisition", which has to do with the fact that most CPA offered by advertisers are about acquiring something (mostly new customers, prospects or leads). Using the term "Cost Per Acquisition" instead of "Cost Per Action" is not incorrect. It is actually more specific. "Cost Per Acquisition" is included in "Cost Per Action", but not all "Cost Per Action" offers can be referred to as "Cost Per Acquisition".

You may refer to the following categories:

Pay per call is a business advertising model for ad listings in popular search engines & directories. This will allow a publisher to be paid from local advertiser every time when a person being interested in any ad provided by the publisher, calls the advertiser.

Pay per call is not restricted only to local advertisers. Many of the pay per call search engines allow advertisers with a national presence to create ads with local telephone numbers.

Pay per delivery is a variation on pay per click used in e-mail marketing. Email marketing campaigns are charged only on the basis of e-mails that are delivered successfully.

Pay per action is a variation on pay per click adopted by many search engines. An advertiser pays a specified amount upon successful completion of some action.

 It is a variant of the CPA (Cost Per Action) model where the advertiser pays the publisher/website only and in proportion to the number of actions committed by the readers or visitors to the website.

In case of Pay per Sale or Cost per Sale, the publisher or website owner is paid on the basis of the number of sales that are directly generated by the ad.