Most smartphones and even mobile phones these days have a function that shows you on a map exactly where you are. This is possible thanks to signals from GPS satellites that orbit the Earth. There are 24 satellites in all, but by receiving the signals from at least three of them, one’s position can be determined fairly accurately.
Photo “GPS Logs from Portland – 2008-2010 – Geoloqi.com” by Aaron Parecki is licensed under CC BY 2.0