About hashing customer information

The information in this article applies only to customer lists you upload, not pixel or Customer Relationship Management (CRM) data.

Hashing is a type of cryptographic security method which turns the information in your customer list into randomised code. The process cannot be reversed.

When you upload your customer list in Ads Manager to create a Custom Audience, the information in your list is hashed before it's sent to Facebook. Facebook uses this hashed information and compares it to our own hashed information. Then, we help build your audience by finding the Facebook profiles that match and create a Custom Audience for you from those matches.

After your Custom Audience is created, the matched and unmatched hashed information is deleted.

• About Custom Audiences from customer lists
• About Custom Audiences