In Fight the Future, the book, a character’s precise location at a precise moment in time can be discerned from a social media post. This happens fourteen years in the future, but it doesn’t have to. Lifehacker reports:

By uploading a photo to Facebook, you’re sharing where and when you took the photo, what kind of phone you’re using, what specific phone you’re using (your unique device ID), your mobile provider, nearby Wi-Fi beacons and cell towers (which can determine your current location), and more. You even share your battery level. …

Facebook can then cross-reference all this data—so Facebook could theoretically record the location of anyone whose face it recognizes, whether or not you tag them. It can also cross-reference this data with everything it already knows about you. And as we’ve seen, this can make Facebook seem positively psychic.