The term cost per action (CPA) is an online advertising digital marketing strategy that allows an advertiser to pay for a specific action from a potential customer. Running a CPA campaign is relatively low risk for the advertiser. This is because the payment only needs to be made when a certain action takes place. CPA campaigns are most often associated with affiliate marketing.
In the CPA model, the maximum risk is borne by the publisher, as income depends on a decent conversion rate. This makes selling on a CPA basis not as attractive as selling ads on a CPM (cost per impression) basis. Some publishers who have extra inventory often fill it with CPA ads.
The effectiveness of advertising inventory purchased by an advertiser can be measured using effective cost per action, or eCPA. eCPA shows the exact amount an advertiser would pay if they bought inventory on a cost-per-action basis. Technically, a CPA could involve any action, not just the acquisition or sale of a customer. However, in practice, CPA means sales. If the desired action is a click, the sales methodology is referred to as CPC, and if the action is a lead, the sales method is referred to as CPL.
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