You’ve probably had this experience before: A store’s own inventory system or its website says that the item you’re looking for is supposed to be, and no one seems to know where it went. That’s why stores are increasingly turning to RFID technology to quickly locate and track in-store inventory.

Radio-frequency identification tags feature electronics so thin that you may not even notice them. They’re expensive compared to plain old cardboard or fabric tags, but deploying them in real life can save a lot of frustration for customers and a lot of labor for stores. Retailers have long used RFID tags for loss prevention, as they can set to trigger alarms as they exit the building.

The Chicago Tribune cites the case of Lululemon Athletica, which tried an RFID tag system out in a few stores in New York City a few years ago. It was out to solve a problem that customers had with online pickup orders.

They would place orders, only to find out later that the store didn’t actually stock that item, and the system would cancel the order. By using RFID tags, they were able to keep this erroneous inventory info out of the system in the first place, cutting down on cancellations.

Another possible use? Theft deterrence, since the tags track the location of an item in real time, even if that item is walking past the door. Amazon’s Go convenience store prototype will use similar technology to eliminate cashiers, letting customers grab their items and automatically scan and pay for them as they enter and exit the store.

The tags also let retailers track how an item moves within a store. If a particular style of pants is brought to the dressing room and then behind often, for example, that that may indicate that customers don’t like the fit, or that the sizing is wrong.

Target is beginning to use the tags mostly for inventory control, finding the tags useful in the stores where they’re being used. Customers may not even realize that they’re being used, and leave RFID tags in fabric tags attached to the clothes behind. Technically, this means that someone could trace your movements while you wear a coat or shirt that uses one of them.

Is that something to fight, or something we’re already used to, like ubiquitous security cameras? First customers need to realize that that the tag are there, then realize how they might be misused.

Want more consumer news? Visit our parent organization, Consumer Reports, for the latest on scams, recalls, and other consumer issues.