Jeff Bezos, Chairman and CEO of Amazon.com, introduces the Kindle Fire at a news conference, Wednesday, Sept. 28, 2011. Mark Lennihan/AP hide caption

itoggle caption Mark Lennihan/AP

Manuel Martinez, the manager of a popular salad restaurant in Washington, D.C., called Sweetgreen, assists a customer. Martinez says customers use the QR code on the wall to learn about promotions and to get discounts. Mallory Benedict/NPR hide caption

itoggle caption Mallory Benedict/NPR