Facebook Custom Audiences is a Facebook advertising offer that lets advertisers take their customer lists and show ads to those people on Facebook.
Through Custom Audiences, advertisers may port their CRM database to Facebook’s platform and reach their existing customers. It can be done using email addresses, phone numbers or Facebook user IDs to make the match.
Advertisers input an email or phone list representing their selected customer segments into the Facebook Power Editor. The list is then be hashed before being sent to Facebook and the system will match the encrypted data against Facebook’s active users.
Use of Facebook Custom Audiences may be expanded to Lookalike Audiences to reach users who are similar to customers.
Facebook Custom Audiences offer is a form of CRM retargeting.