Whether you like it or not, Facebook knows a lot about you. A study released back in 2015 showed that your Facebook Like profile could reveal intricate details about your psychological make-up and preferences, finding, ultimately, that Facebook knows you better than your family, your friends, even your partner. In fact, in some instances, Facebook data revealed more about a person than they even knew about themselves.
That sounds crazy, right? But for every Like, for every comment, for every connection you make on The Social Network, Facebook can match that data against their two billion other profiles to find commonalities and patterns. If you, for example, like ‘Coca Cola’ and ‘Katy Perry’, that probably doesn’t mean much, but Facebook would be able to infer from those likes that you’re more likely to also be interested in, say, ‘Pizza’, though the matching wouldn’t be significant. But then, if you extrapolate that by the hundreds of Likes each person has submitted over time, and the various connections of each individual, you can start to see how clear patterns would emerge. People interested in two of the same things may not have a significantly higher likelihood of liking something else, but having 80-100 Likes in-common would be fairly indicative.
This is how Facebook’s vast data collection system works.