# What does Facebook know about me, and how? **URL:** \ **Category:** Factual Questions\ **Created:** [September 22, 2010, 1:51am UTC](https://boards.straightdope.com/t/what-does-facebook-know-about-me-and-how/554603 "2010-09-22T01:51:44Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\ **Post date:** [September 22, 2010, 1:51am UTC](https://boards.straightdope.com/t/what-does-facebook-know-about-me-and-how/554603/1 "2010-09-22T01:51:44Z")
I am not a member of Facebook. Every now and then, if I’m searching for an old friend or something, I’ll visit someone’s page there. One friend posted one of my long, rambling e-mails because I didn’t have any place of my own to share it. That’s about it. Yesterday, I got a couple e-mails inviting me to join. The From: field is a name I don’t recognize, with an address from [facebookmail.com](http://facebookmail.com). The weird part is in the body of the message. There’s a list of five “other people you may know on Facebook:”, and I do know four of them. They don’t know each other, though. One is my stepmother, who lives in Arizona. One is a college friend who I still keep in touch with. One is a co-worker from 15 years ago in Seattle. (She’s the one who shared my writing.) Another is a guy I worked with in Boston who has since moved back to Mexico. How did Facebook connect me to these people? I share an uncommon last name with my stepmother, so that’s one possibility. (And it may not actually be her; the others have pictures.) I suppose the others may have dropped my name somewhere on their pages, but does Facebook scan everybody’s writing to look for names of people who aren’t members? I wouldn’t call this stalking, exactly, but it’s a little weird for them to know stuff about me that I didn’t tell them. (The picture of the invitor does look familiar, but I can’t place it. If I were to join, I’m not sure I want my first contact to be “do I know you?”) ETA: I may have figured out who sent the invite. If I’m right, she wouldn’t know the other four. ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [September 22, 2010, 1:59am UTC](https://boards.straightdope.com/t/what-does-facebook-know-about-me-and-how/554603/2 "2010-09-22T01:59:19Z")
Someone was looking for you, if facebook can’t find a person it asks you for their email address and offers to send them an email to join. It matched you up with the others because they have your email address in their person email address book and had submitted it to Facebook. Facebook: if HAL had Google. ETA, at this point Facebook likely doesn’t know much about you other then E-mail address and some guesses on who you would know. ---
**Author:** ![Darth\_Panda](https://avatars.discourse-cdn.com/v4/letter/d/ee7513/32.png) [@Darth\_Panda](https://boards.straightdope.com/u/Darth_Panda)\ **Post date:** [September 22, 2010, 2:21am UTC](https://boards.straightdope.com/t/what-does-facebook-know-about-me-and-how/554603/3 "2010-09-22T02:21:48Z")
Why do I get the feeling that someday I’m going to have to send a cyborg back in time to kill Mark Zuckerberg? ---
**Author:** ![Fear\_Itself](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fear_itself/32/19637_2.png) [@Fear\_Itself](https://boards.straightdope.com/u/Fear_Itself)\ **Post date:** [September 22, 2010, 2:37am UTC](https://boards.straightdope.com/t/what-does-facebook-know-about-me-and-how/554603/4 "2010-09-22T02:37:32Z")
Facebook asked your friends to upload their address book; some of them actually did it. Once they had your email address, they matched you with your friends. ---
**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\ **Post date:** [September 22, 2010, 5:38am UTC](https://boards.straightdope.com/t/what-does-facebook-know-about-me-and-how/554603/5 "2010-09-22T05:38:49Z")
Okay, that makes sense so far. Thanks. The follow-up is, why would my friends upload their address books into Facebook? What’s in it for them; are they using Facebook as their everyday e-mail client? (I wonder who that fifth person is, and how he got my address.) ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [September 22, 2010, 5:43am UTC](https://boards.straightdope.com/t/what-does-facebook-know-about-me-and-how/554603/6 "2010-09-22T05:43:38Z")
> [@Robot\_Arm](#): > > The follow-up is, why would my friends upload their address books into Facebook? You let Facebook access your address book on an online e-mail service (e.g. Gmail), and it lists all the people on your address book who are on Facebook. It’s a quick and easy way to find all the people you know on Facebook. ---
**Author:** ![SeaDragonTattoo](https://avatars.discourse-cdn.com/v4/letter/s/df705f/32.png) [@SeaDragonTattoo](https://boards.straightdope.com/u/SeaDragonTattoo)\ **Post date:** [September 22, 2010, 9:30am UTC](https://boards.straightdope.com/t/what-does-facebook-know-about-me-and-how/554603/7 "2010-09-22T09:30:56Z")
That’s why I set up a fake-name gmail account before I joined Facebook, and used that as an alias. No one can find me unless I want them to, so I’m not bothered by high school jackasses from 20 years ago or need to be careful with posting stuff that distant relatives don’t need to know about. ---
**Author:** ![Palooka](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/palooka/32/2902_2.png) [@Palooka](https://boards.straightdope.com/u/Palooka)\ **Post date:** [September 22, 2010, 1:40pm UTC](https://boards.straightdope.com/t/what-does-facebook-know-about-me-and-how/554603/8 "2010-09-22T13:40:18Z")
Wait, [facebookmail.com](http://facebookmail.com)? I think the deeper question is how does a Facebook phishing email know who your friends are. ---
**Author:** ![ZipperJJ](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/zipperjj/32/211_2.png) [@ZipperJJ](https://boards.straightdope.com/u/ZipperJJ)\ **Post date:** [September 22, 2010, 2:16pm UTC](https://boards.straightdope.com/t/what-does-facebook-know-about-me-and-how/554603/9 "2010-09-22T14:16:27Z")
[Facebookmail.com](http://Facebookmail.com) is actually Facebook’s mail domain. ---
**Author:** ![Palooka](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/palooka/32/2902_2.png) [@Palooka](https://boards.straightdope.com/u/Palooka)\ **Post date:** [September 22, 2010, 2:47pm UTC](https://boards.straightdope.com/t/what-does-facebook-know-about-me-and-how/554603/10 "2010-09-22T14:47:40Z")
Oh, man. It actually is. That’s silly of them. ---
**Author:** ![ZipperJJ](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/zipperjj/32/211_2.png) [@ZipperJJ](https://boards.straightdope.com/u/ZipperJJ)\ **Post date:** [September 22, 2010, 4:02pm UTC](https://boards.straightdope.com/t/what-does-facebook-know-about-me-and-how/554603/11 "2010-09-22T16:02:13Z")
I agree. I went to my inbox to double check that when I read the OP.