A hashed list is a coded list that helps Instagram show you relevant ads while also anonymizing and protecting your information. Businesses and organizations that you’ve previously interacted with may want to reach you on Instagram. If you’ve given a company your contact information such as your phone number or email address, and that company decides to advertise on Instagram, you may see one of their ads.

Companies upload a coded list of phone numbers or email addresses to optimize their ad delivery. These coded lists are called hashed lists. Hashed lists are lines of code that ensure Instagram doesn’t receive your actual contact information from the business. Instagram’s system then takes the contact information it already has and turns it into code to see if it matches the code uploaded from the company. If the code matches, Instagram may show a relevant ad.

After the match process is completed, Instagram will delete the hashed list.

Learn more about the ads you see on Instagram.