How a Hidden Bar Code in iPhone Screens Saved Apple Hundreds of Millions of Dollars

Next time you try to wipe a smudge off your iPhone screen, take a closer look. See if you can spot one of the two tiny QR codes etched into its glass.

Chances are you won’t be able to find them. Both codes are tiny—one is the size of a grain of sand and can only be seen with special equipment, while the other, roughly the size of the tip of a crayon, is laser-printed on the reverse side of the glass somewhere along its black border or bezel. The codes are placed on the glass at different stages of manufacturing to help Apple track and reduce defects. They represent the company’s obsessive attention to detail in manufacturing devices such as the iPhone, which has helped it squeeze costs in a traditionally low-margin business.