This document discusses how Facebook Custom Audiences can help businesses create more effective Facebook ads by targeting existing customers. Custom Audiences allows advertisers to upload lists of customer email addresses or phone numbers to reach those they already have a connection with. Setting up a Custom Audience is simple - advertisers just need to upload a CSV file of customer information and then select their Custom Audience when creating a new Facebook ad campaign. This targeted approach can increase ad performance and sales by putting ads in front of an engaged audience.