Facebook’s biggest advantage is the amount of data and information they have on their users, and you can use this to your advantage when targeting your Link Ads.
Within the Facebook Link Ad setup you can target specific end users through interest-based targeting. This type of targeting is best as it allows you to target the end users who are specifically interested in your business and product you are advertising. The data for interest-based targeting has been collected through Facebook user’s likes, interests, apps used, pages liked and their activity on the site.
An audience size indicator is shown within the setup to provide a visual understanding of the potential ad reach from the data entered for the audience, targeting and demographic. Always keep in mind that these are estimates and not guarantees.
Tip: a recommendation would be to target a smaller potential ad reach but more specific users who have an interest in what the advertising are offering, rather than a larger broad audience. In this case less is more!