By CBS News
5:33 PM CST, November 9, 2011
Are you planning to shop online this holiday season? Many companies out there are waiting to track your every internet move, so they can sell you something later or sell information about you to someone else. It's called "retargeting."
Danielle Dafneotis recently bought a purse online from a major retailer. Now, she sees ads for matching shoes on other websites she visits.
Dafeneotis asks, "How did they know I bought that bag a week ago, and now I'm getting specials for shoes?"
They know because when she bought that purse, the company attached what's called a cookie to her computer's browser. It tracks her shopping habits without her knowing.
Privacy expert John Verdi says, when you visit a website, as many as 20 different companies could be monitoring your every move.
It's no coincidence if an ad catches your eye, because chances are it's been placed there specifically for you.
"Different users will almost certainly see different advertisements even when they visit the same website," says Verdi.
If you don't want to be tracked, you can delete cookies or ask advertisers not to follow you, but experts say it's nearly impossible to stop the flow of information. " The reality is that the large internet companies are always one step ahead," says Verdi.
Danielle Dafneotis doesn't mind, "I kind of like it, because I just got two really good deals."
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