Facebook knows literally everything about you

Cambridge Analytica may have used Facebook’sdata to influence your political opinions. But why does least-liked tech company Facebook have all this data about its users in the first place?
Let’s put aside Instagram, WhatsApp and other Facebook products for a minute. Facebook has built the world’s biggest social network. But that’s not what they sell. You’ve probably heard the internet saying “if a product is free, it means that you are the product.”
And