While helping research this article, the author's roommate spent an afternoon in that paranoid state one might have after seeing a horror movie alone late at night. The phone would vibrate, she'd jump in surprise, and then check to make sure it was someone she knew calling her before she answered. There are a lot of scary stories out there about smartphone stalking and people stealing your personal information.
Potential stalkers have two primary ways they can track you via your smartphone. One way is through social engineering, which requires little or no technical expertise. You could be voluntarily giving away personal information or access to your smartphone to someone you know or who gains your trust. If that person chooses, he or she can exploit that information to track where you are and what you're doing, even if you don't want to be tracked.
Another way stalkers can track you is to steal information from your smartphone. This is the more technical side of smartphone stalking. The stalker could gain access to your smartphone, install tracking software or malware, and use that to download your address book, log on to malicious Web sites or even track your location on a map. If your smartphone has a GPS, a stalker could pinpoint the phone's precise location any time it's on with GPS enabled. For more information about geolocating a mobile phone, check out our article on How GPS Phones Work.
The good news is that by taking a few precautions, you can keep potential stalkers at bay. This article reveals ways someone could track you using your smartphone, and it lists things you can do to avoid unwanted attention.