Facebook shares personal information about you that you never submitted to the social network with its advertisers. Of course, you can't delete it from their records.
A paper (PDF) published by researchers at Northeastern University and Princeton University examines how ad targeting works on Facebook.
Let's take a look at what the researchers found:
Say you have a mobile phone number and a landline number, and you've only posted the first one on your Facebook profile. If an advertiser has your mobile number in their database, they can use it to target you with ads on Facebook. If the advertiser also has your landline number, they could target you with ads on that number as well.
But is it possible that they have it if you haven't shared your landline number on Facebook?
You may not have given it to Facebook, but if you gave your landline number to a friend who is also on the social network and has it saved in their address book (which Facebook has access to), then they can associate it with your profile.
As reports , Facebook has previously not admitted that it does this. Furthermore, if you give the social network a mobile phone number solely for two-factor authentication, that number still ends up on advertisers' lists even though it is not publicly visible on Facebook.
Of course, all of the above are not among Facebook's biggest privacy violations, but they prove once again that the company does not care at all about your privacy.
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