Ask HN: Does Facebook sift through your image cache?
I got a strange contact showing up as a friend recommendation. The wierd thing is I don't know the real name of this person and cannot figure out how facebook got it! (And I am pretty sure the other person doesn't know my real name either). So the only possibility I can think of is FB looking through my browser cache or something and doing a face/image detection/recognition of sorts. Any idea ? I am not 100% positive, and I don't work for FB, but it is my understanding that FB doesn't need to look at your cache to determine who you may know. There are several factors to consider in determining if someone may know someone that FB uses. The weight of each factor combined determines the likelihood of the individuals knowing each other. Some of those factors are in no particular order: 1. Mutual friends
1a. If Friend X talks to Person Y a lot, and you a friends with Friend X and you talk to Friend X lot via liking and commenting on FB, there is a higher chance of you knowing Person Y. Compared to if you are just friends with Friend X and don't really communicate with them. 2. Education - did you go to the same school or are you friends with people that went to the same schools. 3. Community - do you live in the same community, city, state. 4. Work - have you worked together or for the same company. Are you friends with people that work with him or her. 5. Are you in a photo, or same album, posted to FB with this individual. For example, if Friend X creates an album and uploads 100 photos to that album. If you are in some of the photos with Friend X and Person Y is in some of the photos with Friend X there may be a good chance you know each other. 6. Did you choose to share your contacts with FB such as using Gmail or Yahoo email? I thought about all the possibilities listed and simply cannot find any of the potentials. It just seems bizarre! I cannot think of any common way FB could've connected us, other than pics. I get random connection suggestions on FB that make me scratch my head as well sometimes, but most, if not all, are people that are 3-4 degrees removed from me. So they are friends of a friend's friend somewhere in the chain. FB makes some guesses based on how much you interact with certain people on the platform. Judging by that it makes weighted judgments of who you may know. So the more you use FB and like/share/comment with your friends, the greater your chances of seeing random friend recommendations that you may not realize there is connection to. Plus, you never know how many people get their entire address book stolen by Facebook without consent (or a drive-by "can facebook app access your contacts?" button that immediately uploads your entire address book back to the mothership; or a linkedin connection/scraping or call record logging on android or half a dozen other aggregate info dump methods people aren't privy to). I'm surprised facebook hasn't tried to create their own spyware-infused browser and computer platform yet. Millions of facebook users think "facebook" is the entire Internet anyway. Not far removed from just giving over your entire life to them. The more I think the more bizzare it was. The reason being, we know each other by synthetic names in a forum (and let me just say anonymity was expected from both of us). So the only way I can think of is somehow the synthetic string/name matched on both of our data somehow like you are describing. They do contact imports from phone and email. That usually sends the signals FB uses for those internet friend type recommendations