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Facebook, How Does it Know?

After getting one of my restaurant review blog posts shared on Facebook I realised that it was a promotional avenue I wasn’t making the most of (or any of) for my blog and started considering whether I should make a ‘page’ for my blog on Facebook. I figured it would be easy enough, go to Facebook and sign up for Page but Facebook makes it somewhat more difficult than that.

Firstly, they make you have a personal account if you’d like a page so I had to sign up with that first which then led Facebook to ask me to find a billion friends and list every interest I’ve ever had.. also where do I work, where did I go to school, how old am I, come on! Give me all your information! Fortunately, I was able to skip past all that and start to make my page.


After I decided what type of ‘business’ I am I then went onto create my page and started getting used to the strange ways of Facebook. It gives you some ‘helpful’ tips on some things but not others and meant I had to use the help pages on more than one occasion – this would never happen with Twitter, just saying.

So, eventually, I was all set up with my Facebook page with custom URL (one of the things you have to stumble upon rather than Facebook giving you a helpful hint about) and everything was going along ok. Although I did have to change my notification settings because Facebook emails you about absolutely everything (and multiple times) if you allow it. My mailbox was getting spammed by Facebook trying to get me to do things and learn as much as about me as it possibly could.

One email came through with a list of people Facebook thought I might know and, in fact, I actually knew all but 1 of them. I looked at my bare account and looked back to the email, wondering how it was that Facebook knew I knew these people. On sign up I had given it my name, my email address, DOB and location and I had looked up one person, who happened to be on this list. The other people listed didn’t know that person though so I still had no idea how it knew.

The email address I provided was one I hadn’t used for anything else, my DOB and location are somewhat useless unless there is more context and it wasn’t like these people had mentioned me by name at some point in their Facebook history so I was still stuck wondering what linked these people.

I stumbled upon a few useful links here and there but mostly it was about the possibility of having mutual friends with the people you had listed as friends, but I had none listed.

Finally, after reading all these different things, it clicked. I had given Facebook my mobile number to verify who I was so I could have my page. At no point did it say “hey, by the way, we’re going to use this information to find people you might know” just that it needed it for verification purposes.

Confused? What this means is that the people who had been ‘found’ for me had given Facebook permission to access their phone contacts to find people they might know. I suppose that Facebook then decides to store all that information (and who knows how much, is it just name and phone number or is it everything that is saved on that contact card?) just in case one of those people decides to sign up in the future.

The disappointing part of this for me is that, even before I had a Facebook account, it already knew things about me. Things I hadn’t given it permission to know. Apparently though, for some reason, other people (and Facebook) thought it was OK to share my information with Facebook without me being aware of it.

All I can suggest at this point is that if an application ever asks for access to your phone contacts, consider the reason why and what information you might be sharing with it, and whether your friends would be ok with that entity having their details.

2 thoughts to “Facebook, How Does it Know?”

  1. I don’t think I have thought about this properly before, but thank you for writing a post on it. :) I don’t have Facebook and I thought about increasing knowledge of my blog through Facebook since it seems very efficient, but I knew I would have to make an account before making a page, which already irritates me. I’ll definitely have to think twice before giving my phone number to some kind of social media app.

    I thought LinkedIn was weird, too.

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