"There's no guarantee that Amazon.com can be a successful company. What we're trying to do is very complicated," said Jeff Bezos in 1999, just five years after launching the online firm. That the firm's founder was so uncertain of its future seems surprising.
Today, 25 years on from when it started, Amazon is one of the most valuable public companies in the world, with Mr Bezos now the world's richest man, thanks to his invention. What started as an online book retailer has become a global giant, with membership subscriptions, physical stores, groceries for sale, its own smart devices and a delivery system which can get things to customers in just an hour.