[nontoxyc]

Facebook has a lot of personal information about you even if you have never had a Facebook account. For example: your GPS location data, approximate age, gender, ethnicity....

Welcome to the future komrade. Sadly, it's not a matter of just "not giving them" your location data. Your devices supply it.

[mixmastamyk]

And your friends too. I dutifully kept a new number out of FB until a friend messaged me with, is this your number right? Xxx-xxx-xxx. They can also tag you and auto tag you through face recognition.