Amazon's Prime Day is so popular it will actually last two days this year, in a sales extravaganza that will take place on 15 and 16 July. Launched in 2015, it's a time when the online retail behemoth expects its sales to go through the roof as shoppers scramble for bargains. Yet Amazon couldn't have become the global phenomenon it is today without a few quirks along the way, from holding meetings in bookstores, to allowing dogs at work and even paying employees to quit. Here are the 39 facts you probably didn't know about Amazon.