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When someone creates a new Facebook account, they see a list of suggested friends. It's surprisingly accurate sometimes. How does Facebook obtain this data?

Some guesses I've thought of so far:

  • People that have searched for the email address used for this account
  • People who have sent Facebook invitations to the email address used for this account
  • People connected to accounts that were accessed from the computer used to create this account

Any others?

  • I think your second point is very probable. Other users might have also connected their email address book in which the email address / name for this account features. – MrWhite Jan 14 '14 at 19:07
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As part of the Facebook sign up process, they have an option to import your email address book, in order to find your friends more easily. And on the mobile app, it does this for your contacts phone numbers that are stored in the phone as well.

They therefore have a database of millions of peoples connections. If you are in one of those people's address book, they will show up in the friends you may know or suggested friends section.

1

We can't know for sure since it's not something they publish (as far as I could find).

Here are my guesses: (Which are mostly based on my experience with Facebook)

  1. An invitation was sent to your email address (as you said).
  2. Your friends searched your name on Facebook in the past.
    • Or searched your email address.
    • Or your phone number.
  3. By your location - GPS or estimated by IP address or any other method.
  4. By your contacts (any data that can be found in your address book):
    • Names
    • Emails
    • Phone numbers
    • Addresses
  5. People you've talked with on SMS.
  6. Your Instagram account - any connection to other people - follower, following etc.
  7. Your WhatsApp chats:
    • Groups.
    • Private chats - also if someone who's not in your contacts just sent you a message, and you haven't even replied.
  8. Your friends data on their accounts:
    • You as a contact on their phone (even if not mutual) - with all the data they saved on you.
    • You as someone they've sent an email to.

I believe there are a lot more, but basically - every piece of data they can collect from you or from people you may know - they collect and use - from location, contact, circles etc. They are fantastic at connecting all this information to get useful insights.


Note: Some of the options are more relevant from mobile and others from desktop.

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