Geolocalization without GPS

Where am I? Where am I headed?

These days, the simplest way to find out your geographical position is to use a GPS receiver or ‘satnav’. A GPS (let’s drop the ‘receiver’) is accurate and works anywhere in the world. GPSs are getting smaller and smaller and performing better and better, and new applications are constantly being found for them. But in spite of how powerful it is, the GPS is not the solution to every geolocalization problem. Where the signals from the GPS satellites can’t get through properly, like indoors or in places surrounded by tall buildings, GPS receivers won’t work correctly.