Advertisers create Custom Audiences on Facebook based on information that they already have, such as your name or contact information. To find out if you're seeing an ad because you're included in a Custom Audience:

1. Click the or near the top-right corner of any ad on Facebook.
2. Select Why am I seeing this?

If you're seeing the ad because you're included in a Custom Audience, you'll see the explanation that the advertiser is reaching you based on their customer list or contact info that you've provided to them outside of Facebook.

As Custom Audiences are based on information that advertisers collect outside of Facebook, advertisers may offer you controls directly, such as making it voluntary to receive offers and promotions from them.

Advertisers can also choose to offer an opt-out for their Custom Audiences on Facebook. If the advertiser does offer an opt-out, you'll see a link to the opt-out when you select "Why am I seeing this?" You can also select Hide all from this advertiser to stop seeing any of an advertiser's ads, both from Custom Audiences and any other way in which the advertiser may be showing you ads on Facebook.

* Nguồn: Facebook