Define CPA marketing.

CPA (Cost Per Action) marketing is a type of affiliate marketing where advertisers pay affiliates a commission only when a specific action is completed by a user. This action could be anything from making a purchase, signing up for a service, filling out a form, downloading an app, or any other predefined action agreed upon between the advertiser and the affiliate network.

In CPA marketing, affiliates are compensated based on the completion of these actions rather than just generating clicks or sales. This model allows advertisers to pay for tangible results rather than just traffic or potential leads. It also gives affiliates the opportunity to earn commissions for a wider range of user actions beyond just making a purchase, making it a more flexible and potentially lucrative form of affiliate marketing.