The Marauder’s Map
The Marauder’s Map is a magical map that shows every inch of Hogwarts School, along with the location of where every person is on campus. It’s a massive system to keep track of anyone, anywhere.
In the real world, someone actually made a Marauder’s Map! It’s a Chrome extension that shows the location of all your friends on Facebook Messenger. In fact, not just your friends, but anyone with whom you’re in a one-on-one or group chat. Yes, you may be sharing your location on Facebook without knowing it.
It’s not just Facebook though. Your smartphone, which is always with you, is sharing your location with several apps that you might not even be aware of.
Right now though, things haven’t become so bad that any random citizen can just bring up a map that shows the location of every other person in the world. A more practical implementation of the Marauder’s Map is in the form of something like the Weasley Clock.