Every time you download an app, search for a web site, send a text, take a picture of a QR code, or drive past a store with your GPS on, your every move may be tracked.
By whom? Your cell phone company.
"They know you were playing Angry Birds. They know that you drove by Sears. They know you drove by Dominos pizza, so they can take that and take a very unique algorithm that can focus on your behavior. It's very impactful," said Mark Johnson with the Loyalty Marketers Association.
Marketing insider Mark Johnson confirms your data trail is worth big bucks to cell phone companies. Many people have no idea this information is being collected, packaged with details about your age and gender, aggregated, and sometimes sold to third parties.
"It does seem creepy that companies are collecting all this information about consumers," said Harrine Freeman, a smartphone user.
Harrine Freeman is so creeped out, she turns off her GPS when she drives and shops. She also clears her browser history.
"I think it's an invasion of privacy. I don't think cell phone companies should sell your information," Freeman said.
All the major cell phone carriers admit to collecting your info. Verizon acknowledges it aggregates the information and sells it to businesses without personally identifying users. The Cell Phone Trade Association would not agree to be interviewed on camera, but some cellular companies say there's an advantage here: you get ads that are relevant and can save you money.
"This is something that consumers are automatically opted into," said Rainey Reitman of the Electronic Frontier Foundation.
Critics say cell phone companies tell customers what data they're collecting by sending them privacy notices that may be difficult to understand and written in fine print. They don't like that consumers who don't want to be tracked have to make the extra effort to "opt out."
"I don't really think that most people are going to review every email they get form their cell phone company and then go through the extra step of opting out of this targeted advertisement," Reitman said.
"The amount of data these cell phone companies have has grown tremendously over the last three to four years. With the rapid rise and proliferation of cell phones it will only continue to grow," Johnson said.