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What is a hashed list?
If you're in the European region, your ad choices are different. Learn more about your ad choices.
A hashed list is a coded list that helps Facebook show you relevant ads, while also anonymising and protecting your information. Businesses and organisations that you've previously interacted with may want to contact you on Facebook. If you've given a company your contact information, such as your phone number or email address, and that company decides to advertise on Facebook, you may see one of their ads.
Companies upload a coded list of phone numbers or email addresses to optimise their ad delivery. These coded lists are called hashed lists. Hashed lists are lines of code that ensure that Facebook doesn't receive your actual contact information from the business. Facebook's system then takes the contact information that it already has and turns it into code to see if it matches the code uploaded from the company. If the code matches, Facebook may show a relevant ad.
After the match process has been completed, Facebook will delete the hashed list.
You can always go to your Ad Preferences page and view advertisers that can choose to show their ads to certain audiences you have been included in based on your activity or information and decide whether these audiences can be used to show you ads.
Learn more about the ads that you see on Facebook.
