Many Americans take advantage of web coupons to save money at their favorite stores.  What they don’t know is that the websites producing the coupons track a good amount of data from the person using the coupon.

“When someone joins a fan club, the user’s Facebook ID becomes visible to the merchandiser. We take that and embed it in a bar code or promotion code.”

“The coupons can, in some cases, be tracked not just to an anonymous shopper but to an identifiable person: a retailer could know that Amy Smith printed a 15 percent-off coupon after searching for appliance discounts at on Friday at 1:30 p.m. and redeemed it later that afternoon at the store.”

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