SAN DIEGO - Odds are that you are reading a smartphone screen right now, or at least have a smartphone nearby. The devices are ever-present, which makes them a huge potential source of information about you.
On phones running Google's Android software or Apple iPhones, the privacy options are buried under several menus. One setting can limit how ads are targeted in the apps you use. Another setting controls the ways your location is tracked throughout the day.
Location settings are particularly confusing because Global Positioning Satellites, cellphone towers and WiFi Internet networks can all be used to determine your location. Adding to the complication on Android phones, the GPS and cell or WiFi tracking are turned off with separate switches.
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Google also logs locations reported by an Android phone throughout the day and plots them on a map. Apple does the same for iPhones.
Rick Clark one of those guys who thought he had read all the fine print. But, he had no idea he was still being tracked -- even though GPS services were turned off.
"(It's) Interesting," Clark said, "and a little bit unnerving at the same time."
"Based on the signal strength of your cellphone and the different tower, your cellphone is able to see where you are down to a couple of feet," explains Steve Beaty, security engineer at the National Center for Atmospheric Research.
The data collected about Clark through his Android phones gave Google enough information to accurately determine where he lived and worked.
"Oh my gosh, time at work," Clark said upon seeing the logs. "How does it know where work is?"
Knowing your current and frequent locations allows phone software companies to make suggestions about nearby activities or advertisers to tailor the content fighting for your dollars.
Apple's iOS software calls their equivalent service "Frequent Locations," which can be found within a submenu of the "Location Services" settings.
But physical location isn't the only way your activities are being tracked.
Google, for example, can analyze the content within the email messages in a customer's Gmail inbox or on a customer's calendar. That data influences the customized results the company serves up on search results or their Google Now app, which offers pieces of current information, based on the information Google knows about you.
As a result, a customer can ask, "When is my flight?"
And get the answer specific to the ticket receipt sitting in their inbox.
The Siri personal assistant on iPhones and iPads works in a similar way.