Massive Amazon warehouses are used to ship and store open-box, refurbished, and returned products

• Amazon operates nearly 300 warehouses worldwide, with some as large as a million square feet.
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• Amazon Warehouse is also a feature on the Amazon website where customers can find deals on pre-owned, used, and open box products.

Despite starting out as an online book seller in 1994, today Amazon is nearly the largest retailer in the world, second only to Walmart.

But while Walmart operates more than 10,000 brick-and-mortar stores in two dozen countries, the core of Amazon's business is online, shipping most of its products directly to homes and businesses.