Facebook begins to roll out cost-per-action advertising service
Facebook has introduced a cost-per-action (CPA) model for advertisers, allowing them more control over what they bid and pay for when advertising through the social networking platform.

The CPA Bidding service will initially run through Facebook’s advertising API, but is expected to be fully rolled out at some stage.
The introduction of the service continues Facebook’s attempts to deliver a more targeted advertising service to brands, allowing them to set a maximum price for what they are willing to pay for the delivery of each action that is important to them e.g each page like or click through their brand receives.
Earlier this week, Facebook also rolled out new updates for its mobile apps on iPad and iPhone.