Amazon’s Prime Day: 5 things to know before you shop

Prime Day, Amazon’s made-up annual shopping event, is upon us.The two-day sale brings in billions of dollars for the company and has become one of its top-grossing events of the year. (The other: Cyber Monday.)Here are five things to know about this year's event, which begins at 3 a.m. Eastern time Monday. (Jeff Bezos, the founder and chief executive of Amazon, owns The Washington Post.)1. What exactly is Prime Day?Amazon created the shopping event five years ago as a way to drum up summer