How Does Facebook Work?

Goddy Ray Devoted online security and privacy advocate 6 min read

Over 2 billion people log into Facebook every single day. The majority of them appreciate a free service that lets them connect with friends, network with potential employers, etc.

However, Facebook also makes money hand over fist. In 2017, Facebook’s revenue was over 40 billion dollars. So, how does Facebook make that much money without charging users?

Advertising. It’s a truism on the net that if you are not the customer, you are the product. Businesses large and small love Facebook ads because they are extremely well targeted. Facebook does not sell your data to advertisers, no.

They sell access to you. Again, businesses love these ads. Facebook ads have a great ROI because they are usually shown only to people who have at least some interest in the product.

According to a recent study by the Pew Research Center , the majority of Facebook users don’t know how it works. So I decided to explain.

How Much Does Facebook Know About You?

The short answer is a lot. Most users fill out a good part of the profile, which might include their location, employer, and marital status. Facebook often knows what high school or college you went to, because you provided that information in an attempt to track down fellow alumni.

It does not end there, though. Facebook monitors everything you do on its network and many of the things you do off its network. Every time you like a page or click on an ad, that data is recorded and used to decide which ad to show you next.

Oh, and Facebook also trains you to help. Do you click on “hide ad” when you see something irrelevant? You just gave them data about what you don’t like.

Facebook stores at least the following:

  • The ads you have clicked on, including when you clicked on them.
  • Apps you have connected.
  • Your conversation history on Facebook Chat.
  • Your email addresses, including inactive ones you removed.
  • All the events you were invited to and whether you went.
  • Where and when you logged in from Facebook.
  • How long you spend looking at something.
  • Where your phone is if you have Facebook installed (be aware that some mobile carriers now pre-install Facebook onto your phone).
  • Your phone number if you set up 2FA.
  • Your credit card number if you purchase anything through Facebook (marketplace or apps).

They can even track some of your activity off of Facebook. If you use Facebook login, then that becomes the same as a connected app. For example, if you use Facebook to connect to popular book review site Goodreads, Facebook will then know which books you read and reviewed, and can then serve you ads for books by the same author or in the same genre.

Facebook pixels, which are invisible, are on some sites and can track you even if you aren’t a Facebook user. When you sign up for Facebook, they already know some things about you. Convenient share to Facebook or like buttons on pages obviously also add to the trove of data.

Now, some of these things are to your benefit. For example, you may need to know where and when you logged in if you suspect somebody has gained access to your account.

Why Is This a Problem?

Getting targeted ads on Facebook is probably something many people consider a reasonable price for using a free service.

However, there are some very real issues with the sheer amount of data Facebook stores about you:

  • It could be stolen. Facebook has been hacked before and will no doubt be hacked again. No matter how responsible Facebook is with your data…
  • Some third parties have access to this data

    , for example the developer of that convenient app you linked. This is how the Cambridge Analytica scandal


  • Bluntly, if your data is worth that much to others, then one could question why they should have it for nothing .

What Can You Do About It?

Well, you can always not use Facebook. However, in today’s connected world that can be difficult. Family members can be quite insistent, employers may want you on there, and freelancers often find Facebook a good way to find new work.

While deleting Facebook altogether might be an option, what should you do if you find Facebook useful but want to minimize the information it has on you.

  • Limit what you put in your profile. For example, don’t include your address or phone number, even if you set it privately (Facebook is notorious for things set as private mysteriously becoming public during an update).
  • Don’t post anything on Facebook , even privately, that would cause embarrassment or potential issues if your employer or a future employer saw it. This includes, but is not limited to: nudes, extreme political views, pictures of yourself in blackface… I would hope nobody reading this would, but social media posts have a habit of coming back to haunt people, even years later
  • Go to Facebook. Tap settings, then ads. From here you can see what Facebook thinks are your interests and what user categories you are put in. You can delete any interests that are inaccurate or embarrassing and X out user categories. We recommend deleting all user categories. They will repopulate, but if you check this regularly, you can keep Facebook from categorizing you too extensively (or inaccurately. Facebook’s algorithm has a habit of guessing your political beliefs wrong). Be aware that some adblockers mistake this page for an ad and block it.
  • You can also download all of your user data and give it a thorough audit.
  • You can clear your Facebook search history .
  • Avoid making purchases through Facebook. If you do, delete your credit card from Facebook’s records right away.
  • Only log in through Facebook if you really need to use a site and it has no other alternative method.
  • Install the Facebook app on your phone only if you regularly use it. If your carrier has installed it, then you should talk to them about it and point out that it may be a privacy violation.
  • Do not upload your contacts to Facebook. This gives information about your friends even if they do not have a Facebook account.
  • Clear the metadata from photos before uploading them.
  • Turn on encryption in Facebook Messenger. This may not stop Facebook itself from reading your messages but could protect them from hackers.

The bottom line, though, is that Facebook gathers a lot of information on you. As with so many things, you need to decide for yourself how to balance privacy and convenience, and work out what data you don’t mind being propagated and what you would rather keep to yourself.

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