Amazon operates a large global supply chain network to support its e-commerce business. It has around 50 warehouses globally, including 20 in the US, to store and fulfill customer orders. Amazon uses a mix of in-house inventory and third-party suppliers to stock products. It aims to deliver most items within one day of ordering to stay competitive. Amazon's supply chain is designed for cost-effectiveness and responsiveness to meet high customer service levels and the wide range of customer demand.