In the media and advertising word, specifically digital, a CPA campaign is cost-per-action. Sometimes, this is also known as a cost-per-acquisition.

With this type of media buy, and advertiser is agreeing to pay a certain fee based on the number of desired outcomes.

The most common type is a direct sale. For example, an advertiser is willing to pay a media seller $1.00 for every confirmed online sale that a publisher drives. If the publisher gets 5,000 users to click an ad, and 10 of them actually end up buying the item advertised, the publisher would expect to receive $10.00 from the advertiser.

The publisher would typically not receive any monetary compensation for the 4,990 users that clicked the ad. They are only compensated for the users that completed a purchase.

Other "actions" that are typical of CPA campaigns include:

• Sign ups for more information

• Subscriptions to email news letters

• Social media "follows" and "likes"

• Phone calls made to the advertiser

• Items placed into an online shopping cart