# How'd They Know THAT? (You may know...) \[How does LinkedIn identify connections?\] **URL:** \ **Category:** Factual Questions\ **Created:** [December 2, 2015, 8:26am UTC](https://boards.straightdope.com/t/howd-they-know-that-you-may-know-how-does-linkedin-identify-connections/739199 "2015-12-02T08:26:17Z")\ **Posts on this page:** 16\ **Page:** 1
**Author:** ![usedtobe](https://avatars.discourse-cdn.com/v4/letter/u/ec9cab/32.png) [@usedtobe](https://boards.straightdope.com/u/usedtobe)\ **Post date:** [December 2, 2015, 8:26am UTC](https://boards.straightdope.com/t/howd-they-know-that-you-may-know-how-does-linkedin-identify-connections/739199/1 "2015-12-02T08:26:17Z")
I don’t do ‘social media’. I have never even _seen_ Facebook, Twitter, snapchat, or even My Space. I dipped a toe into LinkedIn - just enough that I could get a phone number. I now get emails from LinkedIn with pics, names, ages, locations of people I DO KNOW. OK, so they go though my InBox and back-track the addresses. Except for the one about a person I have had absolutely NO electronic (or even electrical) contact. Last saw her in 1978. She spells her name oddly; this HAS to be her, given location and name. I may have done a search on her 12-15 years ago when I did a bit of “whatever happened to…” - but I did not find her (I forgot how she spelled her name). Did they really find that Google search, did a phonetic match on name, and locate this person. The web got scary when I could look up an address and get all the info I needed to program a ballistic missile. Anybody know WAY too much as to how this is done? ---
**Author:** ![Hail\_Ants](https://avatars.discourse-cdn.com/v4/letter/h/dc4da7/32.png) [@Hail\_Ants](https://boards.straightdope.com/u/Hail_Ants)\ **Post date:** [December 2, 2015, 8:46am UTC](https://boards.straightdope.com/t/howd-they-know-that-you-may-know-how-does-linkedin-identify-connections/739199/2 "2015-12-02T08:46:55Z")
This may be an unsatisfying (i.e. boring) answer, but it’s because social media has made the [six degrees of separation theory](https://en.wikipedia.org/wiki/Six_degrees_of_separation) travel at the speed of light (sort of). IOW you both still have (or until sometime had) multiple mutual friends… ---
**Author:** ![Senegoid](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senegoid/32/6606_2.png) [@Senegoid](https://boards.straightdope.com/u/Senegoid)\ **Post date:** [December 2, 2015, 9:09am UTC](https://boards.straightdope.com/t/howd-they-know-that-you-may-know-how-does-linkedin-identify-connections/739199/3 "2015-12-02T09:09:32Z")
Facebook can be downright eerie in some of the connections it figures out. When I first made myself a Facebook account, it immediately presented me a list of people I _might_ know, that I might want to friend. The first name on the list was a second-cousin that I had just seen a few weeks earlier for the first time in about 40 years (at my father’s funeral). I’m guessing she probably made some post about being at that funeral, and that somehow got linked to me. The second name on the list was a friend I had not seen or had any contact with for about 30 years. Since then, it has regularly sent me lists of people I might know, which occasionally include people I actually do know. And some of those are downright eerie, to wonder how Facebook came up with some of those connections. ---
**Author:** ![elbows](https://avatars.discourse-cdn.com/v4/letter/e/b3f665/32.png) [@elbows](https://boards.straightdope.com/u/elbows)\ **Post date:** [December 2, 2015, 9:20am UTC](https://boards.straightdope.com/t/howd-they-know-that-you-may-know-how-does-linkedin-identify-connections/739199/4 "2015-12-02T09:20:11Z")
I always thought it was because people list where they work and where they went to school. That info is out there, they just connect the dots! ---
**Author:** ![jtur88](https://avatars.discourse-cdn.com/v4/letter/j/e9c0ed/32.png) [@jtur88](https://boards.straightdope.com/u/jtur88)\ **Post date:** [December 2, 2015, 12:58pm UTC](https://boards.straightdope.com/t/howd-they-know-that-you-may-know-how-does-linkedin-identify-connections/739199/5 "2015-12-02T12:58:39Z")
Maybe that person looked YOU up. Or you and that person have a registered acquaintance in common. ---
**Author:** ![guizot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/guizot/32/3636_2.png) [@guizot](https://boards.straightdope.com/u/guizot)\ **Post date:** [December 2, 2015, 1:36pm UTC](https://boards.straightdope.com/t/howd-they-know-that-you-may-know-how-does-linkedin-identify-connections/739199/6 "2015-12-02T13:36:24Z")
> [@jtur88](#): > > Maybe that person looked YOU up. Or you and that person have a registered acquaintance in common. Or that person has your phone number, (and the social media website has your number, too). If Facebook, or whatever, is installed on your phone, as a mobile app, or for texting, or whatever, then every person who’s ever had your phone number will eventually show up as “someone you might know,” as well as the people who have assumed the recycled phone numbers of those people. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [December 2, 2015, 1:36pm UTC](https://boards.straightdope.com/t/howd-they-know-that-you-may-know-how-does-linkedin-identify-connections/739199/7 "2015-12-02T13:36:48Z")
There’s also this: > [@Senegoid](#): > > … Since then, it has regularly sent me lists of people I might know, which occasionally include people I actually do know. And some of those are downright eerie, to wonder how Facebook came up with some of those connections. In other words, Facebook screws up and chases blind alleys a lot. But our innate human desire to find patterns & coincidences makes us remember and remark on the occasional lucky hit and ignore the vastly larger number of defective bad guesses FB and the others make. But most of all, most of us are far less anonymous than we think we are. And anyone who does anything on social media is the total opposite of anonymous. They are in effect a celebrity with a full time PR department constantly spamming the planet with their actions, connections, purchases, and possessions. The only amazing thing is how many people don’t get this. ---
**Author:** ![Kevbo](https://avatars.discourse-cdn.com/v4/letter/k/e47774/32.png) [@Kevbo](https://boards.straightdope.com/u/Kevbo)\ **Post date:** [December 2, 2015, 5:18pm UTC](https://boards.straightdope.com/t/howd-they-know-that-you-may-know-how-does-linkedin-identify-connections/739199/8 "2015-12-02T17:18:22Z")
Another trick is that they record peoples searches, and use that data when the unfound person starts an account. So Julie Schmoe may have searched for you a couple years ago, and when somebody with your name shows up, they ask them all if they know Julie. ---
**Author:** ![bump](https://avatars.discourse-cdn.com/v4/letter/b/7c8e57/32.png) [@bump](https://boards.straightdope.com/u/bump)\ **Post date:** [December 2, 2015, 7:00pm UTC](https://boards.straightdope.com/t/howd-they-know-that-you-may-know-how-does-linkedin-identify-connections/739199/9 "2015-12-02T19:00:27Z")
> [@elbows](#): > > I always thought it was because people list where they work and where they went to school. That info is out there, they just connect the dots! Probably that, and some number of common Facebook friends. I know that it and LinkedIn often refer me to people that I might know who are friends or work with people I know, even if I’ve never actually met them. Interestingly enough, it’s pointed out some odd connections that I didn’t know existed- like people from college knowing people I went to middle school with through work. ---
**Author:** ![Ornery\_Bob](https://avatars.discourse-cdn.com/v4/letter/o/da6949/32.png) [@Ornery\_Bob](https://boards.straightdope.com/u/Ornery_Bob)\ **Post date:** [December 2, 2015, 8:04pm UTC](https://boards.straightdope.com/t/howd-they-know-that-you-may-know-how-does-linkedin-identify-connections/739199/10 "2015-12-02T20:04:06Z")
\*I may have done a search on her 12-15 years ago when I did a bit of “whatever happened to…” - but I did not find her (I forgot how she spelled her name). Did they really find that Google search, did a phonetic match on name, and locate this person.\* Absolutely not. All they are doing is mining the data that both of you have provided. It could be as simple as home town or zip code or whatever information that you and she have provided that makes any sort of connection no matter how tenuous. ---
**Author:** ![glowacks](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/glowacks/32/5548_2.png) [@glowacks](https://boards.straightdope.com/u/glowacks)\ **Post date:** [December 2, 2015, 9:22pm UTC](https://boards.straightdope.com/t/howd-they-know-that-you-may-know-how-does-linkedin-identify-connections/739199/11 "2015-12-02T21:22:13Z")
I have gotten a few of these, and I’ve come to the conclusion that it’s because both I and that person have the same person in their email address list. Even if that same person isn’t on Facebook, it doesn’t matter. Yes, this produces a lot of false leads, but as mentioned people tend to just ignore the people that they actually don’t know and focus on the amazing ability of Facebook to know that they know someone with whom they have had no direct electronic connection. It’s the two-step connections that people won’t be aware of. ---
**Author:** ![ThelmaLou](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thelmalou/32/390_2.png) [@ThelmaLou](https://boards.straightdope.com/u/ThelmaLou)\ **Post date:** [December 2, 2015, 9:36pm UTC](https://boards.straightdope.com/t/howd-they-know-that-you-may-know-how-does-linkedin-identify-connections/739199/12 "2015-12-02T21:36:32Z")
Would it help if this guy deleted his cookies regularly? ---
**Author:** ![control-z](https://avatars.discourse-cdn.com/v4/letter/c/eada6e/32.png) [@control-z](https://boards.straightdope.com/u/control-z)\ **Post date:** [December 2, 2015, 9:39pm UTC](https://boards.straightdope.com/t/howd-they-know-that-you-may-know-how-does-linkedin-identify-connections/739199/13 "2015-12-02T21:39:31Z")
> [@ThelmaLou](#): > > Would it help if this guy deleted his cookies regularly? Only if they don’t log into the site. Once you log in, they know who you are. ETA: I don’t mean they know your name, address, etc. just because you created an account. But once you log in they know your email address/username and whatever information you have told them about yourself (which can be a lot if you’re not careful), all your past visits/searches, etc., PLUS all the information they can infer from your contacts. ---
**Author:** ![usedtobe](https://avatars.discourse-cdn.com/v4/letter/u/ec9cab/32.png) [@usedtobe](https://boards.straightdope.com/u/usedtobe)\ **Post date:** [December 2, 2015, 9:39pm UTC](https://boards.straightdope.com/t/howd-they-know-that-you-may-know-how-does-linkedin-identify-connections/739199/14 "2015-12-02T21:39:55Z")
> [@Ornery\_Bob](#): > > \*I may have done a search on her 12-15 years ago when I did a bit of “whatever happened to…” - but I did not find her (I forgot how she spelled her name). > > Did they really find that Google search, did a phonetic match on name, and locate this person.\* > > Absolutely not. All they are doing is mining the data that both of you have provided. It could be as simple as home town or zip code or whatever information that you and she have provided that makes any sort of connection no matter how tenuous. We knew each other in 1970-1971. I used some not-quite-ethical technique to find her in HER hometown (which was NOT my hometown) - in 1978 or 1979. The only connections were: College (student population 22,000) (1970-1971) I lived for 3 years (1977-1979, incl) in her home town. And: about 1/4 of the possible hits are, in fact, people I once knew. And: I am 99.9% asocial. I have lived in this town for 7 years. I have no friends here - every time I deal with another person, some money changes hands. I do not keep any address book - if I can’t remember the email id, I scroll through ‘sent’ emails and copy/paste id’s. Somehow, it found the RE agent I used to sell a house in 2008 - I have had no contact with him since moving here. This suggests they got my address from 2008 and found his name on MLS as agent on the sale. I didn’t give out that address. ---
**Author:** ![Chimera](https://avatars.discourse-cdn.com/v4/letter/c/8e8cbc/32.png) [@Chimera](https://boards.straightdope.com/u/Chimera)\ **Post date:** [December 2, 2015, 10:28pm UTC](https://boards.straightdope.com/t/howd-they-know-that-you-may-know-how-does-linkedin-identify-connections/739199/15 "2015-12-02T22:28:40Z")
Hint: If someone looks at your profile in FB, they’ll show up on your “may know” list for a brief time after that. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [December 2, 2015, 10:45pm UTC](https://boards.straightdope.com/t/howd-they-know-that-you-may-know-how-does-linkedin-identify-connections/739199/16 "2015-12-02T22:45:49Z")
Thread title edited to indicate subject.