When the Waze app on your smartphone, or Google Maps, is telling you the best route to the airport based on current traffic patterns, how do they know where the traffic is? They’re tracking your cell phone and the cell phones of thousands of other users of the applications to see how quickly those cell phones move through traffic. If you’re stuck in a traffic jam, your cell phone reports the same GPS coordinates for several minutes; if traffic is moving swiftly, your cell phone moves as quickly as your car and these apps can recommend routes based on that.
