A: Facebook retargeting allows you to serve ads on Facebook to people who have visited your web site. This is made possible through the use of Facebook's API.
With Perfect Audience Facebook retargeting, a business adds our site tracking tag to their web site code. This tag is completely invisible to visitors and places a unique "cookie" in their browser that lets the user be anonymously identified as having visited your web site. The users cookied in this way make up what we call a Retargeting Audience.
Once you've created an Audience, you can use Perfect Audience to create Facebook ad campaigns that will reach those people on Facebook in ads on the right sidebar or in their News Feed. When your users see these ads, they are reminded about your service and are invited to return and sign up or convert in some way.