Comment 5 for bug 1421623

GPS is most accurate positioning system we have on the phone. However it comes with price, here are some of the bad features of GPS: drains battery, does not work indoors, takes long to get initial location when used first time (or long after last use)

Therefore number of supporting used to leverage those "bad" features of GPS, however those other technologies come at the price.
Namely network based location (wifi, GSM cells) is faster and less power hungry than GPS, but it has lot worse accuracy.

HERE location service uses network based location in order to show user coarse location quickly, while GPS is working on the background to acquire precise location. This can be observer in here maps when actual circle representing accuracy shrinks in the moment GPS location is acquired.
In short we get between 1m to 15m for GPS location, based on number of visible satellites.
but 25m to 30km! accuracy for network based location. 30km is extreme with no visible wifi and only one visible GSM cell tower. Still valid example.