Facebook loves to get to know its users, so it purchases offline financial information on you from 6 of its data partners in the US: Acxiom, Epsilon, Experian, Oracle Data Cloud, TransUnion and WPP.
With this information, Facebook knows about users' household income, and much more. The social network buys the offline data, mixing it with the data it collects on your online activity. Facebook uses the blend of information to customize advertising for you on Facebook, with ProPublica "reports 29,000 categories are offered to advertisers, with 600 filled with third-party data", reports NextPowerUp.
Is there anything Facebook doesn't know about you? Considering its founder Mark Zuckerberg tapes up the webcam on his laptop, I wouldn't put it past them.