Certainly the rationale behind the Universal Product Code made sense. A standardized way to identify individual products would ease inventory management, smooth out supply chains and change the checkout experience. But in the four decades since those grocers in April 1973 adopted the U.P.C. as we still know it today, the bar code has become the core technology that ties together physical commerce with our global information infrastructure.

To drive home the bar code’s overwhelming ubiquity, Brussels-based nonprofit GS1, which maintains international UPC standards, has posted an online ticker to count the number of bar codes scanned around the world each day. According to GS1, the average number of daily scans is more than 5 billion. That’s a sharp increase since the bar code made its commercial debut in 1974 when cashier Sharon Buchanan rang up a 10-pack of Juicy Fruit at a Marsh Supermarket in Troy, Ohio.