When you snap a digital photo using a device that has GPS navigational services enabled, that photo file is embedded with the time, date, location, device information and other "metadata" (data about data). This is called geotagging, and it means that when you post a photo online that was taken with your smartphone, essentially you are uploading a digital file that contains private information about the whereabouts of the original photo.
That data, in conjunction with all the information you've posted on FaceBook about your recent trip to Disney World, your dog's name, information about your kid's soccer tournament, the PTA, etc., provides stalkers with a fairly complete picture of your child's world.
Side note: Keep in mind that many phones upload your pictures to some cloud service automatically. This is a feature that you might consider opting out of on your phone. For example, if you have your Android device configured to back up your phone's photos via your Google Plus profile, it puts a copy of all those photos on your Google Plus Photo page. All of that location data goes with those photos, wherever they may go on the Internet. And guess what? Google has full access to those photos, as well as equal ownership. But that is another story, outlined in your Google terms of service agreement, should you choose to read it.
Parents, here is where you want to pay attention. Pictures of your child in his or her bedroom, at school and elsewhere can provide the rest of the world sufficient information to locate that child, as outlined in this NBC affiliate news story posted to YouTube: https://www.youtube.com/embed/N2vARzvWxwY?rel=0.
What is your recourse? You can either disable geotagging on your smartphone, or disable all location services on your phone (which improves your privacy drastically, but disables your ability to navigate with a map app and renders useless all of your apps that rely on geolocation services).
To learn how to disable geotagging, conduct a Google search on how to disable geotagging coupled with your particular phone type. Sample queries on Google.com are: "How to disable geottagging Android," and "How to disable geotagging iPhone."
For more information, see:
- What is geotagging? Securing yourself, your family and your assets (by FishNet Security)
- Air Force Tech Report on GPS (video)
- GPS educational poster: How GPS Works for your school