On July 15, 2015, Amazon marked the twentieth anniversary of its founding with a “global shopping event” called Prime Day. Over the next 24 hours, starting at midnight, the company offered special discounts every ten minutes to the 44 million users of Amazon Prime, its members-only benefit program. The event was astonishingly successful: Amazon made 34 million Prime sales that day, nearly 20 percent more than it had on Black Friday, the traditional post-Thanksgiving buying bonanza. The company received almost 400 orders per second—all on a single, ordinary day in the middle of summer.