Downloading a retailer's app can bring exclusive sales and optimize your shopping time, but that convenience tends to compromise some privacy.

For instance, creating an online or mobile shopping list or searching for a product on a retailer's app can help the retailer close a deal.

According to Marti, if you leave the part of the store that sells an item on your list, or you leave the store and go to a competitor, the retailer can send a targeted direct sales offer if there was a high-accuracy indoor location system in place. "You would get an exclusive offer that recognizes that you are in a different store to lure you back in."

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